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  1. 04 Mar, 2011 1 commit
  3. 01 Mar, 2011 1 commit
    • Jan Niehusmann's avatar
      drm/i915: fix memory corruption with GM965 and >4GB RAM · 6927faf3
      Jan Niehusmann authored 
      

On a Thinkpad x61s, I noticed some memory corruption when
plugging/unplugging the external VGA connection. The symptoms are that
4 bytes at the beginning of a page get overwritten by zeroes.
The address of the corruption varies when rebooting the machine, but
stays constant while it's running (so it's possible to repeatedly write
some data and then corrupt it again by plugging the cable).

Further investigation revealed that the corrupted address is
(dev_priv->status_page_dmah->busaddr & 0xffffffff), ie. the beginning of
the hardware status page of the i965 graphics card, cut to 32 bits.

So it seems that for some memory access, the hardware uses only 32 bit
addressing. If the hardware status page is located >4GB, this
corrupts unrelated memory.
Signed-off-by: default avatarJan Niehusmann <jan@gondor.com>
Acked-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
      6927faf3
  5. 28 Feb, 2011 2 commits
  7. 24 Feb, 2011 2 commits
  9. 23 Feb, 2011 7 commits
  11. 22 Feb, 2011 3 commits
  13. 21 Feb, 2011 1 commit
    • Indan Zupancic's avatar
      drm/i915: Do not handle backlight combination mode specially · 951f3512
      Indan Zupancic authored 
      The current code does not follow Intel documentation: It misses some things
and does other, undocumented things. This causes wrong backlight values in
certain conditions. Instead of adding tricky code handling badly documented
and rare corner cases, don't handle combination mode specially at all. This
way PCI_LBPC is never touched and weird things shouldn't happen.

If combination mode is enabled, then the only downside is that changing the
brightness has a greater granularity (the LBPC value), but LBPC is at most
254 and the maximum is in the thousands, so this is no real functional loss.

A potential problem with not handling combined mode is that a brightness of
max * PCI_LBPC is not bright enough. However, this is very unlikely because
from the documentation LBPC seems to act as a scaling factor and doesn't look
like it's supposed to be changed after boot. The value at boot should always
result in a bright enough screen.

IMPORTANT: However, although usually the above is true, it may not be when
people ran an older (2.6.37) kernel which messed up the LBPC register, and
they are unlucky enough to have a BIOS that saves and restores the LBPC value.
Then a good kernel may seem to not work: Max brightness isn't bright enough.
If this happens people should boot back into the old kernel, set brightness
to the maximum, and then reboot. After that everything should be fine.

For more information see the below links. This fixes bugs:

  http://bugzilla.kernel.org/show_bug.cgi?id=23472
  http://bugzilla.kernel.org/show_bug.cgi?id=25072

Signed-off-by: default avatarIndan Zupancic <indan@nul.nu>
Tested-by: default avatarAlex Riesen <raa.lkml@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      951f3512
  15. 17 Feb, 2011 3 commits
  17. 16 Feb, 2011 6 commits
  19. 14 Feb, 2011 10 commits
  21. 13 Feb, 2011 4 commits

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