[Bug 97918] [bdw regression 4.8] Severe graphics regression, rainbow glitching and flickering on Intel Broadwell 5500U integrated graphics

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=97918

--- Comment #22 from Mark Spencer <n7u4722r35 at ynzlx.anonbox.net> ---
Finally I updated kernel to 4.9 series so I can give you some feedback. All
tests performed with version 4.9.8

booting with i915.enable_psr=1 -> flickering occurs randomly
booting with i915.enable_psr=1 i915.edp_vswing=2 -> flickering still occurs
randomly
recompiling kernel with whitelist patch
https://bugs.freedesktop.org/attachment.cgi?id=126978 and booting with
i915.enable_psr=1 -> all clear, no flickering!

Conclusion: nothing really changes from previous kernels. Using OpRegion panel
type is still needed for this device to work properly.

I'm not sure about Nicholas but my hardware is 98% identical to his. The reason
he noticed breakup with 4.9 kernel could be that he used to revert the
"infamous" commit d18accc4ef53cc91b93384a5227b787a47f321b4 instead of
whitelisting his device which could conflict with recent code changes.

I wonder what's the ratio between devices which should use Opregion and those
which shouldn't. The proper fix could be to automatically direct device to one
of those groups. As a temporary workaround it would be nice to have runtime
switch to force using OpRegion panel type as recompiling every new kernel with
4 lines of code is nuts especially with flood of kernel updates in recent
times.

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