ACK: [SRU][H/Unstable][PATCH 0/2] Display abnormal on the TGL+4k panel machines

[Tim Gardner]

Acked-by: Tim Gardner <tim.gardner at canonical.com>

On 5/5/21 9:48 PM, Hui Wang wrote:
> BugLink: https://bugs.launchpad.net/bugs/1922885
> 
> The same patches were sent to oem-5.10 for a while, the OEM project
> worked well with these 2 patches. When I sent the patches to oem-5.10,
> I thought the patches are temporary workaround from Intel, they will
> replace them with a real fix. But by now, Intel still uses the patches
> to fix this issue, looks like they are the real fix. So I send them to
> generic kernel of H and Unstable.
> 
> 
> [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(+)
> 

-- 
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Tim Gardner
Canonical, Inc