[PATCH V4] drm/dp_mst: Retrieve extended DPCD caps for topology manager

[Koba Ko]

Thanks for the review.
Sorry for that I thought the review tag should be appended by myself.
One thing to confirm with you, will you or I push this patch to drm-misc-next ?

Thanks a lot.

On Wed, Sep 23, 2020 at 2:01 AM Lyude Paul <lyude at redhat.com> wrote:
>
> One last change I realized we should do is print the name of the AUX adapter
> in question. I don't mind just adding that myself before I push it though so
> you don't need to send a respin.
>
> Going to go push this to drm-misc-next, thanks!
>
> On Tue, 2020-09-22 at 14:53 +0800, Koba Ko wrote:
> > As per DP-1.3, First check DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT.
> > If DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT is 1,read the DP_DP13_DPCD_REV to
> > get the faster capability.
> > If DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT is 0,read DP_DPCD_REV.
> >
> > Signed-off-by: Koba Ko <koba.ko at canonical.com>
> > Reviewed-by: Lyude Paul <lyude at redhat.com>
> > ---
> >  drivers/gpu/drm/drm_dp_mst_topology.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> > b/drivers/gpu/drm/drm_dp_mst_topology.c
> > index e87542533640..63f8809b9aa4 100644
> > --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> > @@ -3686,9 +3686,9 @@ int drm_dp_mst_topology_mgr_set_mst(struct
> > drm_dp_mst_topology_mgr *mgr, bool ms
> >               WARN_ON(mgr->mst_primary);
> >
> >               /* get dpcd info */
> > -             ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd,
> > DP_RECEIVER_CAP_SIZE);
> > -             if (ret != DP_RECEIVER_CAP_SIZE) {
> > -                     DRM_DEBUG_KMS("failed to read DPCD\n");
> > +             ret = drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd);
> > +             if (ret < 0) {
> > +                     drm_dbg_kms(mgr->dev, "failed to read DPCD, ret %d\n",
> > ret);
> >                       goto out_unlock;
> >               }
> >
> --
> Cheers,
>         Lyude Paul (she/her)
>         Software Engineer at Red Hat
>