Comment 9 for bug 653002

Ricardo Salveti (rsalveti) 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

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.