| author | Manjunathappa, Prakash <prakash.pm@ti.com> | |
| Tue, 27 Sep 2011 06:01:28 +0000 (11:31 +0530) | ||
| committer | Vaibhav Hiremath <hvaibhav@ti.com> | |
| Mon, 23 Jan 2012 19:14:26 +0000 (00:44 +0530) | ||
| commit | 346aefad0cb97b57e31d64f1535ef7c41973069a | |
| tree | fddf486464932f074560b8e122701662ea9d308c | tree | snapshot (tar.xz tar.gz zip) |
| parent | 6aeef6fd4d50bb7297d964b2352a3cad9307b59b | commit | diff |
video: da8xx-fb: Fix flicker due to 1 frame delay in updated frame
There is flicker/tearing issue was observed with current FB driver.
Below link to wiki describes the issue and it also has link to
application with which issue can be reproduced.
http://ap-fpdsp-swapps.dal.design.ti.com/index.php/DA8XX_LCDC_Linux_FB_FAQs
Issue is because of 2 active DMA channels ping ponging among them
along with usage of 2 DDR buffer ping pong and application is not
aware of active DMA channel.
Below steps describe issue:
1)Initially assume both buffers FB0 and FB1 are programmed for buffer-0.
2)On EOF0: Program FB0 for buffer-1, indicate(wake up) application
to fill up buffer-0. As FB1 is active and continues to DMA buffer-0
(which is being filled), leading to tearing/flickering issue.
3)On EOF1: Program FB1 for buffer-0, indicate(wake up) application to
fill up buffer-1. As FB0 is active and continues to DMA buffer-1(which
is being filled), leading to tearing/flickering issue.
4)On EOF0: Program FB0 for buffer-1, indicate(wake up) application to fill
up buffer-0. As FB1 is active and continues to DMA buffer-0(which is being
filled), leading to tearing/flickering issue.
...
The above steps also depicts that there is one frame delay for each
frame panned by application.
Patch fixes the issue by keeping track free DMA channel and configures
it in driver PAN callback so that panned frame from application gets
displayed in next frame period.
Signed-off-by: Nellutla, Aditya <aditya.n@ti.com>
Signed-off-by: Manjunathappa, Prakash <prakash.pm@ti.com>
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
There is flicker/tearing issue was observed with current FB driver.
Below link to wiki describes the issue and it also has link to
application with which issue can be reproduced.
http://ap-fpdsp-swapps.dal.design.ti.com/index.php/DA8XX_LCDC_Linux_FB_FAQs
Issue is because of 2 active DMA channels ping ponging among them
along with usage of 2 DDR buffer ping pong and application is not
aware of active DMA channel.
Below steps describe issue:
1)Initially assume both buffers FB0 and FB1 are programmed for buffer-0.
2)On EOF0: Program FB0 for buffer-1, indicate(wake up) application
to fill up buffer-0. As FB1 is active and continues to DMA buffer-0
(which is being filled), leading to tearing/flickering issue.
3)On EOF1: Program FB1 for buffer-0, indicate(wake up) application to
fill up buffer-1. As FB0 is active and continues to DMA buffer-1(which
is being filled), leading to tearing/flickering issue.
4)On EOF0: Program FB0 for buffer-1, indicate(wake up) application to fill
up buffer-0. As FB1 is active and continues to DMA buffer-0(which is being
filled), leading to tearing/flickering issue.
...
The above steps also depicts that there is one frame delay for each
frame panned by application.
Patch fixes the issue by keeping track free DMA channel and configures
it in driver PAN callback so that panned frame from application gets
displayed in next frame period.
Signed-off-by: Nellutla, Aditya <aditya.n@ti.com>
Signed-off-by: Manjunathappa, Prakash <prakash.pm@ti.com>
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
| drivers/video/da8xx-fb.c | diff | blob | history |