Re: [PATCH v3] drm/dp_mst: Retrieve extended DPCD caps for topology manager

From: Koba Ko
Date: Tue Sep 22 2020 - 03:37:51 EST


On Tue, Sep 22, 2020 at 2:11 AM Lyude Paul <lyude@xxxxxxxxxx> wrote:
>
> Hi, sorry I lost track of this until just now. Comments down below:
>
Sorry, the wrong base. I will modify it based on v2 and will send v4.
> On Fri, 2020-09-11 at 11:44 +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@xxxxxxxxxxxxx>
> > Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
> > ---
> > Changelog:
> > 1. Adjust the commit message.
> > 2. use drm_dbg_kms instead and print the return code.
> > ---
> > drivers/gpu/drm/drm_dp_mst_topology.c | 14 +++-----------
> > 1 file changed, 3 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> > b/drivers/gpu/drm/drm_dp_mst_topology.c
> > index 7753c718ddf9..63f8809b9aa4 100644
> > --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> > @@ -3671,8 +3671,6 @@ EXPORT_SYMBOL(drm_dp_read_mst_cap);
> > int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr,
> > bool mst_state)
> > {
> > int ret = 0;
> > - u8 dpcd_ext = 0;
> > - unsigned int dpcd_offset = 0;
> > struct drm_dp_mst_branch *mstb = NULL;
> >
> > mutex_lock(&mgr->payload_lock);
> > @@ -3686,17 +3684,11 @@ int drm_dp_mst_topology_mgr_set_mst(struct
> > drm_dp_mst_topology_mgr *mgr, bool ms
> > struct drm_dp_payload reset_pay;
> >
> > WARN_ON(mgr->mst_primary);
> > - drm_dp_dpcd_read(mgr->aux,
> > - DP_TRAINING_AUX_RD_INTERVAL,
> > - &dpcd_ext, sizeof(dpcd_ext));
> > -
> > - dpcd_offset =
> > - ((dpcd_ext & DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT)
> > ? DP_DP13_DPCD_REV : DP_DPCD_REV);
>
>
> Uh, are you sure you formatted this patch correctly? None of these hunks are present upstream, this looks like it's a diff for the previous version of this patch that you sent out
> >
> > /* get dpcd info */
> > - ret = drm_dp_dpcd_read(mgr->aux, dpcd_offset, 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
>