APPLIED Re: [SRU][OEM-5.10][PATCH 0/2] Display abnormal on the TGL+4k panel machines

[Timo Aaltonen]

On 7.4.2021 11.21, Hui Wang wrote:
> BugLink: https://bugs.launchpad.net/bugs/1922885
> 
> This SRU is only for oem-5.10 temporarily, there are 2 patches in this
> SRU, the 1st patch is for applying the 2nd patch without conflict, and
> the 2nd patch is the key to fix this issue. But the 2nd patch is just
> a workaround from Intel, it is not a real fix, it just disable the
> DC3 clock off support for all TGL psr2 unconditionally, so I only send
> the patches to oem-5.10 kernel since the LENOVO has been pushing us to
> fix the oem bug for long time.
> 
> After Intel has real solution of this issue, will revert the patches
> and send the real solution patches to all ubuntu kernels.
> 
> [Impact]
> On the TGL machines, if the panel is 4k resolution and the i915 driver
> is in PSR2 mode, the display will be abnormal randomly and the
> keyboard reponse is delayed randomly.
> 
> [Fix]
> We reported this issue to Intel and Lenovo shipped a machine to Intel
> developer, they reproduced the issue and they provided a workaroud
> patch.
> 
> [Test]
> Booting the system with patched kernel, open 10+ terminal windows,
> move those windows or resize those windows for 10 mins, the display
> is good. Open a terminal and press 1, 2, 3 and 4 keys rapidly and
> repeatedly, the 1, 2, 3, 4 is showed on the terminal immediately,
> there is no delay between pressing and showing.
> 
> 
> [Where problems could occur]
> After applying these patches, the DC3 clock off mode is disabled
> unconditionally on the TGL+PSR2 machines, this could introduce
> power consumption regression. But we tested the patched kernel on
> different TGL lenovo machines, all power_management test cases passed.
> 
> 
> 
> Gwan-gyeong Mun (2):
>    drm/i915/display: Do not allow DC3CO if PSR SF is enabled
>    UBUNTU: SAUCE: drm/i915/display/psr: Disable DC3CO when the PSR2 is
>      used
> 
>   drivers/gpu/drm/i915/display/intel_psr.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 

the patch actually got merged to drm-tip, so maybe there will be a 
follow-up commit later on, but in the meantime this is now merged to 
oem-5.10, thanks


-- 
t