Re: [PATCH 1/2] drm/i915: Disable Panel Self Refresh (PSR) by default

[Sultan Alsawaf <sultan@kerneltoast.com>]

On Mon, Mar 30, 2020 at 10:51:04AM +0200, Greg KH wrote:
> On Sun, Mar 29, 2020 at 08:30:56PM -0700, Sultan Alsawaf wrote:
> > From: Sultan Alsawaf <sultan@kerneltoast.com>
> > 
> > On all Dell laptops with panels and chipsets that support PSR (an
> > esoteric power-saving mechanism), both PSR1 and PSR2 cause flickering
> > and graphical glitches, sometimes to the point of making the laptop
> > unusable. Many laptops don't support PSR so it isn't known if PSR works
> > correctly on any consumer hardware as of 5.4. PSR was enabled by default
> > in 5.0 for capable hardware, so this patch just restores the previous
> > functionality of PSR being disabled by default.
> > 
> > More info is available on the freedesktop bug:
> > https://gitlab.freedesktop.org/drm/intel/issues/425
> > 
> > Cc: <stable@vger.kernel.org> # 5.4.x
> > Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
> > ---
> >  drivers/gpu/drm/i915/i915_params.c | 3 +--
> >  drivers/gpu/drm/i915/i915_params.h | 2 +-
> >  2 files changed, 2 insertions(+), 3 deletions(-)
> 
> What is the git commit id of this patch in Linus's tree?
> 
> thanks,
> 
> greg k-h

This isn't in Linus' tree. I know for a fact that 5.4 has broken PSR support
that'll never be fixed, but I wasn't sure if PSR was still broken in 5.6.

However, I tested 5.6 for a bit right now and PSR is still broken. And to top it
off, I managed to reproduce some PSR glitches with the drm-tip branch, so
there's currently no kernel in existence with functional PSR. :)

I will send this patch for inclusion in Linus' tree, so please disregard it for
now.

Thanks,
Sultan