[Help][RS780E][mipsel]Screen corruption sometimes

Chen Jie chenj at lemote.com
Tue Aug 23 00:01:21 PDT 2011


在 2011年8月19日 上午10:18,Alex Deucher <alexdeucher at gmail.com>写道:
> > 在 2011年8月8日 下午5:35,Dave Airlie <airlied at gmail.com>写道:
> >> You might want to try some of 3.1-rc1 kernel drm radeon code, Ben
> >> Herrenschmidt did a bunch of powerpc fixes that might
> >> be required on MIPS.
> >>
> > We tried 3.1-rc2, the corruption remains, attachment is the dmesg log
> > from 3.1-rc2.
> The sbios reserves a contiguous chunk of system memory as VRAM.  Does
> your system properly account for this stolen memory?  If not, the
> kernel and the GPU may both be trying to use it.

Not sure I understand it or not, but we're using the sideport way, and
has a dedicated 128M DDR2 memory as VRAM.

1. Is there any way to disable gtt? I tried to hack it and rendered no
display on screen.
2. I've hacked radeon_test_moves():
  * It will allocate N(as much as possible) gtt and vram  bo.
  * For gtt->vram test, It first copies all N gtt bo to N vram bo,
then do the check.
  * For vram->gtt test, it first copies all N vram bo to N gtt bo,
then do the check.

The details are at:
   * http://dev.lemote.com/files/upload/software/temp/Radeon.test/radeon_test.c
   * diff with original radeon_test_moves():

The new bo moving test is pass, but when I changed the bo size to 4M,
the kernel panic with unaligned access at some point after bo moving
test. The original radeon_test_moves() is ok for 4M bo size. Could
someone reviews the new radeon_test_moves() to find if this was caused
by some mistakes of the code or is a potential bug of the platform?

- Chen Jie

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