CMNT[F needs this patch]: [PATCH 0/1][SRU][D/E] UBUNTU: SAUCE: drm/i915: Disable PSR by default on all platforms

[Sultan Alsawaf]

On Mon, Feb 10, 2020 at 05:57:05PM -0800, Sultan Alsawaf wrote:
> BugLink: https://bugs.launchpad.net/bugs/1849947
> 
> In Linux 5.0, PSR (Panel Self Refresh) was enabled by default on capable
> hardware using Intel integrated graphics. On the few consumer laptops that do
> have a panel with PSR support, enabling PSR causes frequent graphical glitches
> that severely impact user experience. Dell laptops are the primary example; it
> appears that no Thinkpads come with panels that support PSR, and it's unknown
> how many other OEMs ship laptops with PSR, so let's just play it safe and
> assume that PSR doesn't work for anyone.
> 
> [Impact]
> PSR is an esoteric power-saving mechanism that will not be dearly missed when
> disabled. The accompanying patch simply toggles PSR off by default in i915; it
> can be re-enabled by the end user at the expense of tainting their kernel. The
> power savings from enabling PSR are slim enough that I didn't observe a
> difference in my laptop's reported power consumption between when I had it
> enabled and disabled.
> 
> [Fix]
> Set the enable_psr parameter in the i915 driver to 0 by default.
> 
> [Test Case]
> I booted up a patched kernel on a laptop with PSR support and the debugfs node
> that reports the status of PSR (/sys/kernel/debug/dri/0/i915_edp_psr_status)
> said it was disabled. The graphical glitches were also gone.
> 
> [Regression Risk]
> Low. This just restores the pre-5.0 behavior of keeping PSR disabled by default
> on capable hardware.
> 
> Sultan Alsawaf (1):
>   UBUNTU: SAUCE: drm/i915: Disable PSR by default on all platforms
> 
>  drivers/gpu/drm/i915/i915_params.c | 3 +--
>  drivers/gpu/drm/i915/i915_params.h | 2 +-
>  2 files changed, 2 insertions(+), 3 deletions(-)
> 
> -- 
> 2.20.1
> 

Just remembered that this patch applies to Focal as well.

Sultan