Methods and systems for updating a buffer

• US 8,692,839 B2
• Filed: 01/25/2008
• Issued: 04/08/2014
• Est. Priority Date: 11/23/2005
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wiley, George Alan, Steele, Brian
• Primary Examiner(s): Nguyen, Phu K
• Application Number:
  US12/020,415
• Publication Number:
  US 20080129749A1
• Time in Patent Office: 2,265 Days
• Field of Search: 345/1.1, 345/1.2, 345/1.3, 345/2.1, 345/2.2, 345/2.3, 345/530, 345/556, 345/559, 345/560, 345/501, 370/216, 370/242, 370/389, 370/397, 370/399, 370/409, 707/3, 707/101, 455/450, 455/572
• US Class Current: 345/539
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 5/12 Synchronisation between the display unit and other units, e.g. other display units, video-disc players
• CPC Class Codes: G09G 5/393 Arrangements for updating the contents of the bit-mapped memory
• CPC Class Codes: G09G 5/395 Arrangements specially adapted for transferring the contents of the bit-mapped memory to the screen G09G5/399 takes precedence

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.

Claims

1. A method for updating a buffer having a plurality of lines associated with a display to prevent image tearing, comprising:

(a) determining a read line position in the buffer, the read line position indicating a line currently being read from the buffer, wherein the buffer is written to by a first processor and is read by a second processor;

(b) partitioning the buffer into at least a first section that is safe to update and a second section that must not be updated based on the read line position; and

(c) writing data at a line of the first section to update the buffer, wherein the line follows the second section based on the read line position.

2. The method of claim 1, further comprising the step of the first and second processors communicating remotely through a communication link.

3. The method of claim 1, wherein the first processor updates the buffer based on a first event at the first processor that is triggered by a second event at the second processor.

4. The method of claim 3, further comprising:

(d) scheduling the first event by writing to a register to enable the triggering of an interrupt that causes the first event based on the second event; and

(e) triggering the second event at the second processor based on the read line position of the buffer.

5. The method of claim 3, wherein the first event comprises a link wakeup event when the communication link is in hibernation mode.

6. The method of claim 1, wherein the first and second processors comprise host and client controllers of a Mobile Display Digital Interface (MDDI) link.

7. The method of claim 6, wherein a first controller comprises a Mobile Station Modem (MSM) baseband processor, and wherein a second controller comprises a display controller.

8. The method of claim 1, wherein the buffer comprises a frame buffer used for refreshing a display.

9. A system for updating a buffer having a plurality of lines associated with a display to prevent image tearing, comprising:

means for determining a read line position in the buffer, the read line position indicating a line currently being read from the buffer, wherein the buffer is written to by a first processor and is read by a second processor;

means for partitioning the buffer into at least a first section that is safe to update and a second section that must not be updated based on the read line position; and

means for writing data at a line of the first section to update the buffer, wherein the line follows the second section based on the read line position.

10. The system of claim 9, wherein the first and second processors communicate remotely through a communication link.

11. The system of claim 9, wherein the first processor updates the buffer based on a first event at the first processor that is triggered by a second event at the second processor.

12. The system of claim 11, further comprising:

means for scheduling the first event by writing to a register to enable the triggering of an interrupt that causes the first event based on the second event; and

means for triggering the second event at the second processor based on the read line position of the buffer.

13. The system of claim 11, wherein the first event comprises a link wakeup event when the communication link is in hibernation mode.

14. The system of claim 9, wherein the first and second processors comprise host and client controllers of a Mobile Display Digital Interface (MDDI) link.

15. The system of claim 14, wherein the host controller comprises a Mobile Station Modem (MSM) baseband processor, and wherein the client controller comprises a display controller.

16. The system of claim 9, wherein the buffer comprises a frame buffer used for refreshing a display.