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

[Ricardo Salveti]

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(-)