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

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Date:   Tue, 22 Sep 2020 15:37:32 +0800
From:   Koba Ko <koba.ko@...onical.com>
To:     Lyude Paul <lyude@...hat.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        dri-devel@...ts.freedesktop.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Anthony Wong <anthony.wong@...onical.com>
Subject: Re: [PATCH v3] drm/dp_mst: Retrieve extended DPCD caps for topology manager

On Tue, Sep 22, 2020 at 2:11 AM Lyude Paul <lyude@...hat.com> 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@...onical.com>
> > Reviewed-by: Lyude Paul <lyude@...hat.com>
> > ---
> > 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
>