Re: [PATCH] drm/amd/display: fix the ability to use lower resolution modes on eDP

[Hamza Mahfooz]

On 9/14/23 17:04, Hamza Mahfooz wrote:
> On 9/14/23 16:40, Harry Wentland wrote:
> > On 2023-09-14 13:53, Hamza Mahfooz wrote:
> > > On eDP we can receive invalid modes from dm_update_crtc_state() for
> > > entirely new streams for which drm_mode_set_crtcinfo() shouldn't be
> > > called on. So, instead of calling drm_mode_set_crtcinfo() from within
> > > create_stream_for_sink() we can instead call it from
> > > amdgpu_dm_connector_mode_valid(). Since, we are guaranteed to only call
> > > drm_mode_set_crtcinfo() for valid modes from that function (invalid
> > > modes are rejected by that callback) and that is the only user
> > > of create_validate_stream_for_sink() that we need to call
> > > drm_mode_set_crtcinfo() for (as before commit cb841d27b876
> > > ("drm/amd/display: Always pass connector_state to stream validation"),
> > > that is the only place where create_validate_stream_for_sink()'s
> > > dm_state was NULL).
> >
> > I don't seem to see how a NULL dm_state in
> > create_validate_stream_for_sink() (or create_stream_for_sink() for that
> > matter) has an impact on the drm_mode_set_crtcinfo() call. That one 
> > depends
> > on !old_stream and &mode.
>
> If we look back to commit 4a2df0d1f28e ("drm/amd/display: Fixed
> non-native modes not lighting up") it seems like the intent was to only
> have drm_mode_set_crtcinfo() called for
> amdgpu_dm_connector_mode_valid(). Since, even if we go that far back
> create_stream_for_sink()'s dm_state was only NULL when it was called
> from amdgpu_dm_connector_mode_valid().
>
> > It does look like &mode is an empty mode if we can't find a 
> > preferred_mode,
> > though. Not sure if that can cause an issue.
>
> I don't think it should be an issue, since before commit 4a2df0d1f28e
> ("drm/amd/display: Fixed non-native modes not lighting up") we always

I meant to refer to commit bd49f19039c1 ("drm/amd/display: Always set
crtcinfo from create_stream_for_sink") here.

> called drm_mode_set_crtcinfo() in the aforementioned case (and only for 
> that case).
>
> > Harry
> >
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2693
> > > Fixes: cb841d27b876 ("drm/amd/display: Always pass connector_state to 
> > > stream validation")
> > > Signed-off-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
> > > ---
> > >   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++--
> > >   1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c 
> > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > index 933c9b5d5252..beef4fef7338 100644
> > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > @@ -6128,8 +6128,6 @@ create_stream_for_sink(struct 
> > > amdgpu_dm_connector *aconnector,
> > >       if (recalculate_timing)
> > >           drm_mode_set_crtcinfo(&saved_mode, 0);
> > > -    else if (!old_stream)
> > > -        drm_mode_set_crtcinfo(&mode, 0);
> > >       /*
> > >        * If scaling is enabled and refresh rate didn't change
> > > @@ -6691,6 +6689,8 @@ enum drm_mode_status 
> > > amdgpu_dm_connector_mode_valid(struct drm_connector *connec
> > >           goto fail;
> > >       }
> > > +    drm_mode_set_crtcinfo(mode, 0);
> > > +
> > >       stream = create_validate_stream_for_sink(aconnector, mode,
> > >                            to_dm_connector_state(connector->state),
> > >                            NULL);
--
Hamza