Re: [PATCH 2/4] drm/amdgpu/display: don't assert in set backlight function

["Kazlauskas, Nicholas" <nicholas.kazlauskas@xxxxxxx>]

On 2021-03-04 1:41 p.m., Alex Deucher wrote:
> On Thu, Mar 4, 2021 at 1:33 PM Kazlauskas, Nicholas
> <nicholas.kazlauskas@xxxxxxx> wrote:
> > On 2021-03-04 12:41 p.m., Alex Deucher wrote:
> > > It just spams the logs.
> > >
> > > Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
> >
> > This series in general looks reasonable to me:
> > Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
> >
> > > ---
> > >    drivers/gpu/drm/amd/display/dc/core/dc_link.c | 1 -
> > >    1 file changed, 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> > > index fa9a62dc174b..974b70f21837 100644
> > > --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> > > +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> > > @@ -2614,7 +2614,6 @@ bool dc_link_set_backlight_level(const struct dc_link *link,
> > >                        if (pipe_ctx->plane_state == NULL)
> > >                                frame_ramp = 0;
> > >                } else {
> > > -                     ASSERT(false);
> >
> > Just a comment on what's actually going on here with this warning:
> >
> > Technically we can't apply the backlight level without a plane_state in
> > the context but the panel is also off anyway.
> >
> > I think there might be a bug here when the panel turns on and we're not
> > applying values set when it was off but I don't think anyone's reported
> > this as an issue.
> >
> > I'm not entirely sure if the value gets cached and reapplied with the
> > correct value later, but it's something to keep in mind.
>
> It doesn't.  I have additional patches here to cache it:
> https://nam11.safelinks.protection.outlook.com/?url=https:%2F%2Fcgit.freedesktop.org%2F~agd5f%2Flinux%2Flog%2F%3Fh%3Dbacklight_wip&amp;data=04%7C01%7Cnicholas.kazlauskas%40amd.com%7Cf259e9290b0e4ffbc87308d8df3d3121%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637504801203988045%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=4ROSclecKkfu2km3YeeM7sZK%2FP%2BcC8BajHSxJXQQCRw%3D&amp;reserved=0
>
> Alex

That's aligned with my expectations then.

I can take a peek at the branch and help review the patches.

Regards,
Nicholas Kazlauskas

> > Regards,
> > Nicholas Kazlauskas
> >
> > >                        return false;
> > >                }
> >
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