[PATCH 05/14] drm/i915/dp: Initialize the link parameters during HW readout

[Imre Deak]

On Tue, Jul 23, 2024 at 11:34:58AM +0300, Kandpal, Suraj wrote:
> 
> 
> > -----Original Message-----
> > From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Imre
> > Deak
> > Sent: Monday, July 22, 2024 10:25 PM
> > To: intel-gfx at lists.freedesktop.org
> > Subject: [PATCH 05/14] drm/i915/dp: Initialize the link parameters during
> > HW readout
> >
> > Initialize the DP link parameters during HW readout. These need to be up-
> > to-date at least for the MST topology probing, which depends on the link
> > rate and lane count programmed in DPCD. A follow-up patch will program
> > the DPCD values to reflect the maximum link parameters before the first
> > MST topology probing, but should do so only if the link is disabled
> > (link_trained==false).
> >
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_dp.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 1e43e32e05199..421e970b3c180 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -3352,8 +3352,11 @@ void intel_dp_sync_state(struct intel_encoder
> > *encoder,
> >
> >       intel_dp_tunnel_resume(intel_dp, crtc_state, dpcd_updated);
> >
> > -     if (crtc_state)
> > +     if (crtc_state) {
> >               intel_dp_reset_link_params(intel_dp);
> > +             intel_dp_set_link_params(intel_dp, crtc_state->port_clock,
> > crtc_state->lane_count);
> > +             intel_dp->link_trained = true;
> 
> Why are we setting link_trained as true here.

link_trained indicates whether the output is enabled or not, which must
be in sync with crtc_state being NULL (output disabled) or not NULL
(output enabled).

> Regards,
> Suraj Kandpal
> > +     }
> >  }
> >
> >  bool intel_dp_initial_fastset_check(struct intel_encoder *encoder,
> > --
> > 2.44.2
>