Hi,
On 2/23/21 6:25 PM, Hans de Goede wrote:
Hi,
I've been working with various reporters to try and get the sometimes severe
gfx glitches which people are seeing with kernel >= 5.10.9 resolved, see the
following bugs:
1843274 - i915 GPU Hang with kernel 5.7 on Haswell (Acer C720P Chromebook)
1925346 - Screen glitches after updating to Kernel 5.10.10
1925903 - Flickering UI elements, screen instability (Wayland)
1931065 - Frequent i915 hangs
I've written 2 patches 2 address this and asked users to test Fedora-kernel
scratch-builds with those patches added.
The first patch is i915-revert.patch, this reverts 3 troublesome commits
which were first added in 5.10.9 these commit change the i915 mitigations
for a year old i915 CVE which IIRC was mostly about data leaking from a
previous GPU context to the next. These patches enable these mitigations
on more GPU models, where they were previously disabled because they were
causing issues...
Reporters have reported a 100% success-rate in getting rid of the gfx
issues with these 3 reverts.
The second patch is i915-fixes.patch, this cherry-picks 3 patches from
-next instead (these were suggested by i915 upstream) and this also helps
for most users, but some users still report some rendering artifacts
(but overall things are much better).
Upstream has gone silent on the issue of there still being rendering
artifacts with the 3 cherry-picked fixes unfortunately.
Given that we are getting more and more bug-reports about this I think
that we should be do something about this downstream. Upstream seams
to be aiming for fixing things, rather then reverting, so going with
i915-fixes.patch will stay the closest to what I expect to land in
5.10.y and 5.11.y at some point.
The bug reports for this keep coming in; and it seems that this is
fully resolved for all reporters except one by the i915-fixes.patch which
I attached earlier; and for the one reporter who is still seeing some
rendering glitches things are much improved, so I think he is also
hitting a different issue.
Here is the full lists of bugs which I'm aware of which all have this
as root cause:
1843274 - i915 GPU Hang with kernel 5.7 on Haswell (Acer C720P Chromebook)
1922511 - Recent upgrades caused smearing/tearing
1925346 - Screen glitches after updating to Kernel 5.10.10
1925903 - Flickering UI elements, screen instability (Wayland)
1931065 - Frequent i915 hangs
https://gitlab.freedesktop.org/drm/intel/-/issues/3099
So unless there are any objections I would really like to move forward
with adding i915-fixes.patch to the Fedora 5.10.y kernels.
Note I'm also working on getting the 3 -next commits:
e627d5923cae ("drm/i915/gt: One more flush for Baytrail clear residuals")
d30bbd62b1bf ("drm/i915/gt: Flush before changing register state")
1914911f4aa0 ("drm/i915/gt: Correct surface base address for renderclear")
which are in i915-fixes.patch added to Greg's stable kernels.
Regards,
Hans