MX2007006198A - Methods and systems for updating a buffer - Google Patents

Abstract

The present invention relates to methods and systems for updating a buffer. In one aspect, the present invention provides a method for updating a buffer, which includes strategically writing to the buffer to enable concurrent read and write to the buffer. The method eliminates the need for double buffering, thereby resulting in implementation cost and space savings compared to conventional buffering approaches. The method also prevents image tearing when used to update a frame buffer associated with a display, but is not limited to such applications. In another aspect, the present invention provides efficient mechanisms to enable buffer update across a communication link. In one example, the present invention provides a method for relaying timing information across a communication link.

Description

METHODS AND SYSTEMS TO UPDATE AN INTERMEDIATE MEMORY FIELD OF THE INVENTION The present invention relates generally to methods and systems for updating a buffer. Very particularly, the invention relates to methods and systems for updating a buffer through a communication link.

BACKGROUND OF THE INVENTION In the field of interconnection technologies, the demand for ever-increasing data rates, especially in regard to video presentations, continues to grow. The Mobile Screen Digital Interface (MDDI) is a cost effective low power consumption transfer mechanism that allows the transfer of data at very high speeds in a short range communication link between a guest and a customer. MDDI requires a minimum of just four cables plus power for bidirectional data transfer that delivers a maximum bandwidth of up to 3.2 Gbits per second. In an application, MDDI increases reliability and decreases power consumption in collapsible phones by significantly reducing the number of wires running through a hinge of the equipment to interconnect the digital baseband controller with an LCD screen and / or a camera. This reduction of cables also allows equipment manufacturers to reduce development costs by simplifying the designs of sliding or folding equipment. When controlling an LCD screen through an MDDI link, a problem that arises refers to the flickering of images when the screen is updated. Usually, what is needed is a conversion of prolonged persistence or an update rate that is higher than what the human eye can perceive. The long persistence conversion results in blurring of images when images appear to move. Therefore, it is desirable that the screen has a high refresh rate. However, a typical problem that occurs is the tearing of images. The problem is that, while the screen is being updated at a high speed, the frame buffer associated with the screen is being filled at a slower speed. As a result, the displayed image can reflect both updated information and information from the previous image within the same frame from the screen. In a solution, multiple buffers are used and the information of the images is cycled through multiple buffers to avoid the problem of tearing of images described above. This includes what is commonly referred to as "double buffering" approaches. However, the drawback of such a solution is clearly the increased cost and space requirements for chips in execution. Therefore, what is needed are methods and systems to allow buffer update solutions to solve the problems described above while meeting the cost and space requirements of MDDI applications.

SUMMARY OF THE INVENTION The present invention relates to methods and systems for updating a buffer. In one aspect, the present invention provides a method for updating a buffer, which includes strategically writing to the buffer to allow simultaneous reading and writing to the buffer. The method eliminates the need for a double buffering, resulting in space savings and cost of execution compared to conventional buffering approaches. Among other advantages, the method avoids tearing images when used to update a frame buffer associated with a screen, but is not limited to such applications. In another aspect, the present invention provides efficient mechanisms to allow updating of the buffer through a communication link. In an example, the present invention provides a method for transmitting timing information through a communication link. However, the method is not limited to transmit timing information, and can be used in more general contexts as understood by those skilled in the art based on the present teachings. Further embodiments, features, and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention are described in more detail below with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE FIGURES The attached figures, which are incorporated in the present invention and form a part of the detailed description, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and enable those skilled in the art to make and use the invention. Figure 1 is a block diagram illustrating an exemplary environment using a Digital Mobile Screen Interface (MDDI). Figure 1A is a diagram of a digital data device interface coupled to a digital device and a peripheral device. Fig. 2 is a block diagram illustrating an MDDI link interconnection according to an embodiment of the example of Fig. 1. Fig. 3 is an example illustrating the problem of tearing images. Figure 4 is a process flow diagram illustrating a method for updating a buffer according to the present invention. Figure 5 illustrates examples of the method of Figure 4. Figures 6A, 6B illustrate buffer read / write strategies. Figure 7 is a process flow diagram illustrating a method for transmitting information from timing through a communication link according to the present invention. Figure 8 illustrates an exemplary signal timing diagram for initiating the awakening of the MDDI link to transmit timing information. The present invention will be described with reference to the appended figures. The figure where an element first appears is typically indicated by the digits to the left in the corresponding reference number.

DETAILED DESCRIPTION OF THE INVENTION The present description details one or more embodiments that incorporate the characteristics of the invention. The described embodiments simply exemplify the invention. The scope of the invention is not limited to the described modalities. The invention is defined by the appended claims thereto. The described modalities, and references in the description to "one modality", "an exemplary embodiment", etc., indicate that the described modalities may include a particular characteristic, structure or feature but each modality does not necessarily include the particular feature, structure or feature. In addition, such phrases do not they necessarily refer to the same modality. Even when a particular feature, structure or feature is described in relation to a modality, it is understood that it is within the knowledge of one skilled in the art to effect said characteristic, structure or feature in connection with other modalities whether or not they are explicitly described. The embodiments of the invention can be executed in hardware, wired microprogramming, software or any combination thereof. The embodiments of the invention can also be executed as instructions stored in a machine-readable medium, which can be read and executed through one or more processors. A machine readable medium can include any mechanism for storing or transmitting information in machine readable form (e.g., a computing device). For example, a computer-readable medium may include read-only memory (ROM); random access memory (RAM); magnetic disk storage medium; optical storage medium; fast memory devices; electrical, optical, acoustic or other forms of propagated signals (for example, carrier waves, infrared signals, digital signals, etc.), and others. In addition, wired microprogramming, software, routines, instructions can be described in this invention as doing some actions. However, it should be appreciated that such descriptions are merely for convenience and that said actions are in fact the result of 'computing devices, processors, controllers, or other devices that perform wired microprogramming, software, routines, instructions, etc.

Mobile screen digital interface (MDDI) The mobile screen digital interface (DDI) is a low-power, cost-effective transfer mechanism that allows the transfer of serial data at very high speed over a short communication link. Scope between a guest and a client. Next, MDDI examples will be shown with respect to a camera module contained in a top folding frame of a mobile phone. However, it will be apparent to those skilled in the art that any module having functionally equivalent characteristics a.l. Camera module could easily be substituted and used in embodiments of the present invention. In addition, according to the embodiments of the invention, an MDDI guest may comprise one of several types of devices that may benefit from the use of the present invention. For example, the host could be a portable computer in the form of a handheld device, portable computer or similar mobile computing device. It could also be a Personal Data Assistant (PDA), a paging device, or one of many wireless phones or modems. Alternatively, the guest could. be a portable entertainment or presentation device such as a portable CD or DVD player, or a gaming device. In addition, the host may reside in a host device or control element in a variety of other widely used or planned commercial products for which a high-speed communication link with a customer is desired. For example, a guest could be used to transfer data at high speeds from a video recording device to a storage-based client for enhanced response, or to a larger high-resolution display screen. A household appliance, such as a refrigerator that incorporates an on-board inventory or computer system and / or Bluetooth connections for other devices. Home, they may have enhanced deployment capabilities when operating in a Bluetooth or Internet connected mode, or have reduced cabling needs for in-the-door screens (a client) and keyboards or scanner (client) while the computer electronics or control systems (guest) reside elsewhere in the cabinet. In general, those skilled in the art will appreciate the wide variety of modern electronic devices and appliances that can benefit from the use of this interface, as well as the ability to feed back older devices with information transport at higher data rates using limited numbers of available conductors on any existing or newly added connectors or cables. At the same time, an MDDI client can comprise a variety of useful devices to present information to an end user, or present information from a user to the host. For example, a micro-screen incorporated into glasses or lenses, a projection device incorporated in a hat or helmet, a small screen or even a holographic element incorporated in a vehicle, such as in a window or windshield, or- loudspeaker, headphones or sound to present high quality sound or music. Other display devices include projectors or projection devices used to present information at meetings, or for films and television images. Another example would be the use of touch pads or touch-sensitive devices, speech recognition input devices, scanner of security, and so on, to which one can resort to transfer a significant amount of information from a device or system user with little actual "input" other than the user's sound or touch. In addition, assembly stations for computers and equipment of carts or desktops and fasteners for cordless telephones can act as interface devices for end users or other devices and equipment, and may employ clients (input or output devices such as a mouse) or guests to assist in the transfer of data, especially when high-speed networks are involved. However, those skilled in the art will readily recognize that the present invention is not limited to those devices, there being many other devices on the market, and proposed for use, which are intended to provide end users with high quality images and sound, either in terms of storage and transport or in terms of presentation in reproduction. The present invention is useful for increasing the performance of the data among various elements or devices to allow the high data rates necessary to obtain the desired user experience. Figure 1A is a diagram of a digital data device interface 100 coupled to a device digital 150 and a peripheral device 180. The digital device 150 may employ, but is not limited to, a cell phone, a personal data assistant, a smart phone or a personal computer. In general, the digital device 150 can include any type of digital device that serves as a processing unit for digital instructions and the processing of digital presentation data. The digital device 150 includes a system controller 160 and a link controller 170. The peripheral device 180 may include, but is not limited to, a camera, a bar code reader, an image scanner, an audio device, and a sensor. In general, the peripheral device 180 can include any type of audio, video or image capture and display device in which the digital presentation data is exchanged between a peripheral and a processing unit. The peripheral device 180 includes control blocks 190. When the peripheral 180 is a camera, for example, the control blocks 190 may include, but are not limited to, lens control, white or intermittent LED control and shutter control. The digital presentation data may include digital data representing audio, images and multimedia data. The digital data interface device 100 it transfers digital presentation data at a high speed over a communication link 105. In one example, an MDDI communication link can be used which supports bidirectional data transfer with a maximum bandwidth of 3.2 Gbits per second. Other high data transfer rates that are higher or lower than this exemplary speed can be supported, depending on the communication link. The digital data interface device 100 includes a message interpretation module 110, a content module 120, a control module 130 and a link controller 140. The link controller 140, which is located within the interface of digital data 100, and the link controller 170, which is located within the digital device 150, establish the communication link 105. The link controller 140 and the link controller 170 may be MDDI link controllers. The MDDI standard of the Electronic Video Standards Association ("VESA"), which is incorporated in the present invention by reference in its entirety, describes the requirements of a high-speed digital packet interface that allows portable devices to transport images. from small portable devices to larger external screens. MDDI applies a miniature connector system and thin flexible cable ideal for linking computing, communications and entertainment devices to emerging products, such as supportable micro-screens. It also includes information on how to simplify connections between guest processors and a display device to reduce the cost and increase the reliability of these connections. Link controllers 140 and 170 establish a communication path 105 based on the VESA MDDI Standard. US patent number 6,760,772, entitled Generation and Implementation of a Communication Protocol and Interface for Transfer of High-Speed Data Signals, issued to Zou et al. July 6, 2004 ("772 patent") discloses a data interface for transferring digital data between a guest and a customer in a communication path using linked packet structures to form a communication protocol for presentation data. The embodiments of the invention shown in Patent 772 focus on an MDDI interface. The signal protocol is used by link controllers, such as link controllers 140 and 170, configured to generate, transmit and receive packets that form the communications protocol, and to form digital data in one or more packet types. data, at least one residing in the host device and coupled to the client through a communication path, such as communication path 105. The interface provides a high-speed, bidirectional, low-power data transfer mechanism and cost effective over a short-range "serial" type data link, which leads to execution with miniature connectors and thin flexible cables. One embodiment of the link controllers 140 and 170 establishes the communication path 105 based on the teachings of the 772 patent. The 772 patent is incorporated herein by reference in its entirety. In other embodiments, the link controllers 140 and 170 may be a USB link controller or both may include a combination of controllers, such as, for example, an MDDI link controller and another type of link controller, such as, for example, , a USB link driver. Alternatively, the link controllers 140 and 170 may include a combination of controllers, such as an MDDI link controller and a single link for exchanging recognition message between the digital data interface device 100 and a digital device 150. link 140 and 170 can additionally support others types of interfaces, such as an Ethernet or RS-232 serial port interface. Additional interfaces can be supported, as will be known to those skilled in the art, based on the teachings shown herein. Within the digital data interface device 100, the message interpretation module 110 receives commands from, and generates response messages through the communication link 105 for the system controller 160, interprets the command messages, and guides the content of information of the commands to an appropriate module within the digital data interface device 100. The content module 120 receives data from the peripheral device 180, stores the data and transfers the data to the system controller 160 through the communication link 105 The control module 130 receives information from the message interpreter 130, and guides the information to the control blocks 190 of the peripheral device 180. The control module 130 can also receive information from the control blocks 190 and guide the information to the module of interpretation of messages 110. Figure 1 is a block diagram illustrating an exemplary environment utiliz I'm going through an MDDI interface. In the example of figure 1, MDDI is used to interconnect modules through a hinge of a folding telephone 100. Referring to Figure 1, a lower folding section 102 of the folding telephone 100 includes a Mobile Station Modem (MSM) baseband chip 104. MSM 104 is a band controller digital base. An upper folding section 114 of the foldable telephone 100 includes a Liquid Crystal Display (LCD) module 116 and a camera module 118. Referring still to Figure 1, an MDDI link 110 connects the camera module 118 to the MSM 104. Typically, an MDDI link controller is integrated in each of the camera module 118 and MSM 104. In the example of FIG. 1, an MDDI Guest 122 is integrated in a camera module 112, while an MDDI client 106 resides in the MSM side of the MDDI link 110. Typically, the MDDI guest is the master controller of the MDDI link. In the example of Figure 1, the pixel data of the camera module 118 is received and formatted in MDDI packets by the MDDI Guest 122 before being transmitted in the MDDI link 110. The MDDI client 106 receives the MDDI packets and the -converts to pixel data of the same format as generated by the camera module 118. The pixel data is then sent to an appropriate block in the MSM 104 for processing.

Referring still to Figure 1, an MDDI link 112 connects the LCD module 116 to the MSM 104. In the example of Figure 1, the MDDI link 112 interconnects an MDDI guest 108, integrated in the MSM 104, and an MDD1 client 120 integrated in the LCD module 116. In the example of figure 1, image data generated by an MSM 104 graphics controller is received and formatted in MDDI packets by the MDDI guest 108 before being transmitted in the MDDI link 112. The MDDI client 120 receives the MDDI packets and re-converts them into image data for use by the LCD 116 module. Typically, the data The images are stored in buffer memory using a frame buffer before being used to update the LCD screen. Figure 2 is a block diagram illustrating the MDDI link interconnection 112 according to the example of Figure 1. As described above, one of the MDDI link functions 112 is to transfer image data from the MSM 104 to the LCD module 116. A frame interface (not shown in Fig. 2) connects the MDDI link controller 120 to the modules of the LCD module 116. Similarly, another frame interface (not shown in Fig. 2) connects the MDDI link controller 108 to appropriate modules of MSM 104. Typically, the MDDI link controller 108 represents the controller host of the MDDI link, while the MDDI link controller 120 represents the MDDI client driver. However, other executions can reverse the functions of the two controllers. The MDDI link 112 includes a minimum of four cables, comprising two cables for data signals 202 and 204 and two cables for test signals 206 and 208, in addition to two cables for power signals 210 and 211. The data signals 202 and 204 are bidirectional. Accordingly, the data can be transmitted in any direction (from the guest to the client and vice versa) using data signals 202 and 204. The strobe signals 206 and 208 are unidirectional, and can only be activated by the host controller of the link. Accordingly, in the example of FIG. 2, only host controller 108 can activate strobe signals 206 and 208.

Method and systems for updating a buffer As described above, MDDI can be used to connect a baseband processor (MSM 104 in Figure 2, for example) and a graphics controller (LCD module 116 in figure 2, for example). The baseband processor channels image information, typically received from a. camera sensor, to the controller graphics, which uses the image information to create a deployment image. Typically, the graphics controller employs one or more frame buffers to store the image information received from the baseband processor before it is used to generate the display image. As described above, tearing images is a problem that occurs. This happens when the image information is being read from the frame buffer at a slower or faster speed than the speed at which it is being written to the frame buffer. Now we will describe methods and systems for updating a buffer, which, among other advantages, solves the problem of tearing images. However, it should be noted that methods and systems according to the present invention are not limited to the specific exemplary embodiments where they will be described or where they are being used in an MDDI environment. In addition, methods and systems of the present invention can be employed in various applications that use buffering, and which can benefit from the advantages of the present invention.

Tearing of images Figure 3 illustrates two examples of tearing images that may occur while reading from and / or written to a buffer. The diagram in Figure 3 shows traces of read and write indicators as functions of the position and time of the buffer. The read indicator represents the position in the buffer that is being read. The write indicator indicates the position in the buffer where it is being written. In the example of Figure 3, the position of the buffer is defined in terms of pixel position in the buffer. In the first example of Figure 3, the buffer is being read at a slower speed than what is being written. This is illustrated by the relative inclinations of the read and write indicator lines 302 and 304. It can be seen that the read and write indicator lines 302 and 304 intersect at time t0. Before the time to, the pixels in the buffer are read before being updated. After time t0, the pixels are updated before being read. Therefore, within the same table (from time 0 to time ti), the pixels in the positions 0 to po (corresponding to the pixel position read at time t0) are read with previous image information in relation to pixels from position p0 to the last pixels in the buffer memory, which are read with updated image information. The result is image tearing with a lower portion of the image reflecting newer image information in relation to a higher portion of the image. In the second example in figure 3, the buffer is being read at a faster speed than what is being written. This is illustrated through relative inclinations of read and write indicator lines 302 and 306. The read and write indicator lines 302 and 306 intersect at time t2. Before time t2, the pixels in the buffer are being updated before being read. After time t2, the pixels are being read before being updated. Accordingly, within the same frame (from time ti to time t3), the pixels at positions 0 to p2 (corresponding to the pixel position read at time t2) are read with newer image information in relation to the pixels from position p2 to the last pixels in the buffer memory, which are read with previous image information. The result is image tearing with an upper portion of the image reflecting newer image information in relation to a lower portion of the image.

Method for updating a buffer Now we provide a method to update, in a strategic way, a buffer. The method avoids image tearing when used to update a frame buffer associated with a screen. The method can also be used in other buffer applications based on its apparent advantages, as will be described in the present invention. Fig. 4 is a process flow diagram 400 illustrating a method for updating a buffer according to the present invention. Process flow diagram 400 begins at step 410, which includes determining a reading line position in the buffer. The reading line position indicates a line that is currently being read from the buffer. Typically, step 410 is accomplished by determining the value of a read indicator that points to the reading line position in the buffer. Step 420 includes dividing the buffer into at least one first section that is safe to update and a second section that must not be updated based on the position of the reading line. Here it can be observed that the division of the buffer memory does not refer to a physical division but a logical one of the intermediate memory. In addition, a logical division of The buffer is not fixed and can change, as will be understood from the teachings of the present invention. The first section of the buffer includes lines from the buffer that have been read within the current buffer reading cycle based on the position of the reading line. The first section also includes lines from the buffer that can be updated based on the position of the reading line. In other words, the first section includes lines whose contents have hardly been read or lines that can be updated before the position of the reading line reaches them based on the reading speed of the buffer and the reading speed of the reading. the buffer The lines that can not be updated before the position of the reading line reaches them based on the reading speed of the buffer and the writing speed of the buffer belong to the second section of the buffer. In other words, the lines in the second section of the buffer are those for which there is not enough time to update before they have to be read. Accordingly, the lines of the second section of the buffer must be updated during the last reading cycle of the buffer.

Step 430 includes updating the buffer by writing data in a line of the first section following the second section based on the position of the reading line. Typically, the buffer is updated in a position where it is safe to update, as described above, and which has already been read during the last reading cycle of the buffer. In one embodiment, step 430 includes writing data in a line of the first section immediately following the last line of the second section. Other variations of step 430 are also possible, as will be apparent to those skilled in the art based on the teachings shown herein.

Illustrating examples Figure 5 provides examples illustrating the method described above in Figure 4. Figure 5 shows three examples A, B and C of reading a buffer 500. For purposes of illustration only, buffer 500 is shown including 352 data lines. A read indicator 510 indicates the position of the reading line in the buffer. The sections labeled with the Roman numeral "I" represent the lines belonging to the first section of the buffer as described above. The sections labeled with the Roman numeral "II" represent lines belonging to the second section of the buffer memory, as described above In Example A, the shaded area "I" represents lines of the first section of the buffer that they have already been read during the current reading cycle of the buffer In the example, this area includes lines 1 through m-1. The reading indicator 510 indicates that the m line is currently being read. "II" in example A represents the lines of the buffer 500 that can not be updated based on the current position of the read indicator 510. In other words, there is not enough time to update the lines in the "II" area based on the current position of the reading indicator 510 and the read and write speeds for the buffer, it can be seen that the first section of the buffer memory also includes an area n or shaded "I" below area "II". This "I" area belongs to the first section since it is safe to update, but it should not be updated because it has not been read during the current reading cycle of the buffer. Updating the unshaded area "I" before your. reading, would result in image tearing, as described in Figure 3, where the upper portion of the image reflects previous image information with relation to the lower portion of the image. In the example B, the shaded area represents lines of the buffer memory that have already been read during the current reading cycle of the buffer memory. In the example, this area includes lines 1 to 351. Read indicator 510 indicates that line 352 is currently being read. Therefore, the area "II" in example B represents the lines that must be updated based on the position of the current reading line. The lines in area "II" can not be updated based on the position of the current reading line and the read and write speeds for the buffer, and belong to the second section of the buffer based on the description The lines in the "I" area belong to the first section of the buffer memory, and are sure to update.To update the buffer, the writing can start in the "I" area.The data can be written in a line in area "I" that immediately follows area "II." This corresponds to line m in example B. Example C illustrates a scenario after one shown in B. In example C, reading indicator 510 has rotated and is reading the m line of the buffer, therefore the lines that precede the reading indicator in the buffer belong to the first section of the buffer memory, and they can be updated. The lines in the "II" area must have been updated during the last write cycle for the buffer due to the position of the current reading line. The lines in the area "II" can not be updated, and belong to the second section of the buffer as described above. In other words, the lines in the "II" area must contain updated information due to the position of the reading line, since there is not enough time to update them before they have to be read. The shaded area "I" represents lines of the first section of the buffer that are safe to update, but should not because they have not been read during the last reading cycle of the buffer.

Buffer Reading / Writing Strategies Here buffer reading / writing strategies are described to avoid tearing images or equivalent problems related to buffering update. The buffer updating strategies, according to the present invention, further eliminate the need for the commonly adopted "double buffering" technique. Rather, a memory is used simple intermediate, which results in space savings and execution costs. The present invention is not limited to the exemplary strategies described herein, and variations that are apparent to those skilled in the art are also considered within the scope of the present invention. Figures 6A and 6B illustrate read / write strategies of the buffer according to the present invention. The diagrams of Figures 6A and 6B show traces of the read indicator 612 and the write indicators 614 and 616 as position functions and buffer time functions. In the examples of FIGS. 6A and 6B, the buffer position is defined in terms of pixel position in the buffer, which can be equivalently replaced with any other buffer memory position measurement, such as the line number , for example. Referring to Figure 6A, an exemplary buffer read / write strategist is shown on two buffer read cycles. In the first reading cycle, from time 0 to time ti, the first half of the buffer is updated, while all the contents of the buffer are read. In the second cycle of reading the buffer, from time ti to time t2, the second half of the buffer is updated, while all the contents of the buffer are read. It can be seen that the first half of the buffer, during the second reading cycle, contains updated information that was written to the buffer during the first reading cycle. The second half of the buffer, during the second cycle, is updated before being read as shown by the write indicator 614 preceding the read indicator 612 in time on the second reading cycle. Accordingly, in both read cycles, the data read from the buffer belongs to the same updated buffer cycle, and no image tear occurs. Figure 6B illustrates another exemplary buffer read / write strategy on two buffer read cycles. During the first reading cycle, the first half of the buffer is updated from time t0 to time ti. During the second reading cycle, the second half of the buffer is catalyzed time ti to time t2. It can be seen that writing for the buffer begins at time t0 during the first cycle so that, during the first cycle, the entire buffer is read with an initial information content and not an updated content due to the writing process. On the other hand, writing in the buffer ends at a time t2 during the second cycle so that, during the second cycle, the entire buffer contains updated information content when it is read. This is shown by. the write indicator 616 preceding the reading indicator 612 in time on the second reading cycle. Accordingly, the image tear will not occur in both reading cycles in the example of Figure 6B.

Update buffer through a communication link Methods and systems for updating a buffer according to the present invention can be used in a variety of applications. In an application, as described above, the .de update approach. The buffer can be used to update a frame buffer associated with a screen. In another application, the buffer is remotely updated, where it is written by a first processor and read by a second processor, and wherein the first and second processors communicate through a communication link. For example, the first and second processors represent a band processor MSM base and an LCD module, respectively, that communicate through an MDDI link, as illustrated in Figure 2. In some applications, synchronization between the first and second processors will be required. Methods and systems related to synchronization will now be provided to allow updating of the buffer through a communication link. As will be understood by those skilled in the art based on the present teachings, some aspects of the methods and systems that will be presented, can be applied to synchronization problems in general, and are not limited to synchronization. the remote buffer. In one aspect, the synchronization between the first and second processors includes programming a first event in the first processor that is activated by a second event in the second processor. This is typically done by writing to a register to allow the revival of an interruption that causes the first event in the first processor whenever the second event occurs in the second processor. For example, in a remote buffer update application, where the buffer is updated by the first processor and read by the second processor, the first event may represent the need to start writing to the buffer, while the second event may represent that the reading indicator has finished a complete cycle of reading the buffer. The second event can then be activated in the second processor based on the position of the reading line in the buffer. In another aspect, methods are provided for transmitting synchronization information through the communication link. The methods may be employed to transmit synchronization information related to the buffer update, as described above, for example. Figure 7 is a process flow diagram 700 illustrating a method for transmitting timing information through a communication link between a first processor and a second processor, when the communication link is in hibernation mode. The process flow diagram 700 begins in step 710, which includes scheduling a time event in the first processor to transmit timing information to the second processor. The time event can be a periodic event as required by the specific application. For example, in the case of a buffer update application, the time event may be related to the position of the reading line in the buffer. Step 720 includes initiating the awakening of a link through a first processor at the occurrence of the time event. For example, in the case of a buffer update through an MDDI link, where an MDDI client is located on the side of the LCD module of the interconnection, the MDDI client can initiate a link awakening by directing the data signal to a logic to notify the MDDI guest that the buffer should be updated. Subsequently, step 730 includes detecting link arousal in the second processor (e.g., an MDDI guest on the MSM side of the MDDI interconnect), and using the wake-up timing of the detected link to synchronize the first and second processors with with respect to the timing information that is being transmitted. For example, in the case of a buffer update through an MDDI link, when the MDDI guest detects the wake-up of the link by the MDDI client, it can be synchronized with the MDDI client with respect to the update start time of the MDDI client. the buffer As will be appreciated by those skilled in the art based on the teachings shown herein, the The method described in Figure 7 can be extended to transmit any type of timing information through a communication link, and is not limited to buffer refresh timing purposes. The advantages of this method are the saving of the link and the transmission of information by simply awakening the link. Fig. 8 illustrates an exemplary timing diagram 800 for initiating link awakening in order to transmit timing information through an MDDI interconnect. For example, the MDDI interconnection may be such as that described above with reference to FIG. 2 with an MDDI guest located in the MSM and an MDDI client located in the LCD module. Accordingly, the MDDI client would initiate an awakening to transmit buffer update information to the MDDI host, which, in turn, would initiate the update of the buffer located in the LCD module. In the example of Figure 8, the signal vsinc_aperture 802 represents a value written to a record in the MDDI host to allow awakening in the host based on the 80inc vsinc signal. Awakening in the host occurs whenever the value of vsinc_awake 802 is high. The signal vsinc 806 represents a value of a signal "vertical synchronization", which occurs in the client and is related to the buffer update time. For example, vsinc 806 increases whenever the read indicator has wrapped and is reading from the start of the buffer. The active_link 804 signal represents whether the data signal of the MDDI interconnection is active or in hibernation. The signal mddi_clierite_ awaken 808 represents a signal in the client, which responds to vsinc 806 to wake the client. In the example of figure 8, vsinc_aperture 802 is set in the host at time A. At time B, the MDDI link enters hibernation mode. At time C, vsinc 806 increases indicating that the buffer needs to be updated by the guest. As a result, mddi_cliente_pertiente 808 also increases to awaken the client and thus trigger the awakening of the link. The client initiates the awakening of the link by activating the data signal of the interconnection, and the link is activated in time D. Subsequently; vsinc_aperture 802 and mddi_cliente_despertar return to zero, and the guest detects the awakening of the link and begins to update the buffer in the client.

Conclusion Although several modalities of this invention have been described above, it should be understood that they have been presented by way of example only, and not as a limitation. It will be apparent to those skilled in the relevant art that various changes can be made in form and detail without departing from the spirit and scope of the invention. Therefore, the scope and scope of the present invention should not be limited by any of the modalities described above, but should only be defined in accordance with the following claims and their equivalents.

Claims (19)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as a priority: CLAIMS

1. - A method for updating a buffer having a plurality of lines, comprising: (a) determining a reading line position in the buffer, said reading line position indicating a line that is currently being read from the memory intermediate; (b) divide the buffer into at least one first section that is safe to update and a second section that must not be updated based on the position of the line read; and (c) writing data in a line of the first section to update the buffer, where the line follows the second section based on the position of the line read. 2. - The method according to claim 1, characterized in that the position of the

Reading line is determined through the determination of a reading indicator value.

3. The method according to claim 1, characterized in that the first section of the buffer memory comprises at least one of: (i) lines of the buffer that have been read in a last reading cycle of the buffer; and (ii) lines of the buffer that can be updated based on the position of the reading line.

4. - The method according to claim 4, characterized in that (ii) further comprises buffer lines that can be updated before the position of the reading line reaches said lines based on a memory read speed intermediate and a buffer write speed.

5. The method according to claim 1, characterized in that the second section of the buffer memory comprises lines of the buffer memory that can not be updated before the position of the reading line reaches said lines based on a speed of buffer reading and a buffer writing speed.

6. - The method according to claim 5, characterized in that the second section of the buffer also comprises lines that must have been updated during a last reading cycle of the buffer memory.

7. - The method according to claim 1, wherein the buffer is written by a first processor and read by a second processor.

8. The method according to claim 7, characterized in that the first and second processors communicate remotely through a communication link.

9. The method according to claim 8, characterized in that the first processor updates the buffer based on a first event in the first processor that is activated by a second event in the second processor.

10. The method according to claim 9, further comprising: (d) programming the first event by writing to a register to enable the activation of an interruption that causes the first event based on the second event; and (e) shoot the second event in the second processor based on the position of the line read from the buffer.

11. The method according to claim 10, characterized in that the first event represents a wake-up event of the link when the communication link is in hibernation mode.

12. The method according to claim 8, characterized in that the first and second processors represent guest and client controllers of a Mobile Screen Digital Interface (MDDI) link.

13. The method according to claim 9, characterized in that the first controller represents a base station processor of Mobile Station Modem (MSM), and wherein the second controller represents an LCD controller.

14. The method according to claim 13, characterized in that the buffer represents a frame buffer used to update an LCD screen.

15. The method according to claim 14, characterized in that the tearing of the image on the screen is substantially avoided.

16. A method for transmitting timing information through a communication link between a first processor and a second processor, wherein the The communication link is in hibernation mode, comprising: scheduling a time event in the first processor to transmit the timing information to the second processor; initiate the awakening of a link through a first processor in the occurrence of the time event; and detecting the link awakening in the second processor, and using the wake-up timing of the detected link to synchronize the first and second processors with respect to the transmitted timing information.

17. - The method according to claim 16, characterized in that the communication link represents a Mobile Screen Digital Interface (MDDI) link.

18. The method according to claim 17, characterized in that the first and second processors represent the MDDI client and the MDDI guest, respectively.

19. The method according to claim 18, characterized in that the timing information represents a buffer update time associated with a screen that is being controlled through the MDDI link.