[Maverick][ti-omap4][SRU][pull-request] Reduce GFX_FIFO_UNDERFLOW issue while using SGX

[Tim Gardner]

On 12/22/2010 09:06 PM, Ricardo Salveti wrote:
> SRU Justification:
>
> Impact: While using SGX acceleration on Pandaboard, it's quite normal to face
> the GFX_FIFO_UNDERFLOW issue, that disable the display entirely. The only
> way to get the screen back to work is to reset it, or by changing to a text mode
> session and then getting back to X11. This issue makes practically impossible
> to use and stress the SGX driver on a Full HD monitor.
>
> Fix: While TI still didn't provide a proper way to fix is, a valid
> workaround was
> proposed to use the writeback buffers for GFX. The proposed patches are all
> already applied at Natty's branch, and this is basically a backport of them for
> Maverick.
>
> Testcase: Just run Unity using the SGX driver on a Full HD monitor, and try to
> use it normally, and your screen will probably get black with the following
> message at your dmesg:
> [ 404.169006] omapdss DISPC error: GFX_FIFO_UNDERFLOW, disabling GFX
> After applying these patches, you should be able to normally use Unity, without
> heading into any underflow issue.
>
> BugLink: https://bugs.launchpad.net/bugs/653002
>
> The following changes since commit 6aba79f8f85b937596373cda8e266b823395996e:
>
>    Ubuntu-2.6.35-903.19 (2010-11-16 18:32:27 -0700)
>
> are available in the git repository at:
>    git://kernel.ubuntu.com/rsalveti/ubuntu-maverick.git
> omap4-reduce-underflow-issue
>
> Archit Taneja (2):
>        OMAP: DSS2: Fix FIFO Threshold calculations for dispc pipelines
>        OMAP: DSS2: Use Writeback buffers for GFX as a temporary fix
>
> Pavel Nedev (1):
>        OMAP: DSS2: Fix array size which stores dispc fifo sizes
>
>   arch/arm/plat-omap/include/plat/display.h |    2 +-
>   drivers/video/omap2/dss/dispc.c           |   29 +++++++++++-
>   drivers/video/omap2/dss/display.c         |   25 ++++++----
>   drivers/video/omap2/dss/dsi.c             |   20 ++++++--
>   drivers/video/omap2/dss/dss.h             |    1 +
>   drivers/video/omap2/dss/wb.c              |   70 +++++++++++++++++++++++++++-
>   6 files changed, 127 insertions(+), 20 deletions(-)
>

Fetch my tree from 'git://kernel.ubuntu.com/rtg/ubuntu-maverick.git 
ti-omap4' to verify that I've applied your patches correctly. You should 
see:

   CC      drivers/video/omap2/dss/wb.o
drivers/video/omap2/dss/wb.c: In function 'wb_buffer_state_store':
drivers/video/omap2/dss/wb.c:49: error: implicit declaration of function 
'dss_get_mainclk_state'

rtg
-- 
Tim Gardner tim.gardner at canonical.com