linux-kernel - RE: [PATCH v6 8/8] drm/msm/dp: Handle eDP mode

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Date:   Thu, 31 Mar 2022 06:02:28 +0000
From:   "Sankeerth Billakanti (QUIC)" <quic_sbillaka@...cinc.com>
To:     "dmitry.baryshkov@...aro.org" <dmitry.baryshkov@...aro.org>,
        "Sankeerth Billakanti (QUIC)" <quic_sbillaka@...cinc.com>
CC:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "freedreno@...ts.freedesktop.org" <freedreno@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "robdclark@...il.com" <robdclark@...il.com>,
        "seanpaul@...omium.org" <seanpaul@...omium.org>,
        "swboyd@...omium.org" <swboyd@...omium.org>,
        quic_kalyant <quic_kalyant@...cinc.com>,
        "Abhinav Kumar (QUIC)" <quic_abhinavk@...cinc.com>,
        "dianders@...omium.org" <dianders@...omium.org>,
        "Kuogee Hsieh (QUIC)" <quic_khsieh@...cinc.com>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "sean@...rly.run" <sean@...rly.run>,
        "airlied@...ux.ie" <airlied@...ux.ie>,
        "daniel@...ll.ch" <daniel@...ll.ch>,
        quic_vproddut <quic_vproddut@...cinc.com>,
        "Aravind Venkateswaran (QUIC)" <quic_aravindh@...cinc.com>
Subject: RE: [PATCH v6 8/8] drm/msm/dp: Handle eDP mode_valid differently from
 dp

Hi Dmitry,

> On Wed, 30 Mar 2022 at 19:04, Sankeerth Billakanti
> <quic_sbillaka@...cinc.com> wrote:
> >
> > The panel-edp driver modes needs to be validated differently from DP
> > because the link capabilities are not available for EDP by that time.
> >
> > Signed-off-by: Sankeerth Billakanti <quic_sbillaka@...cinc.com>
> 
> This should not be necessary after
> https://patchwork.freedesktop.org/patch/479261/?series=101682&rev=1.
> Could you please check?
> 

The check for DP_MAX_PIXEL_CLK_KHZ is not necessary anymore but we need
to return early for eDP because unlike DP, eDP context will not have the information
about the number of lanes and link clock.

So, I will modify the patch to return after the DP_MAX_PIXEL_CLK_KHZ check if is_eDP is set.

> > ---
> >  drivers/gpu/drm/msm/dp/dp_display.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
> > b/drivers/gpu/drm/msm/dp/dp_display.c
> > index 8bafdd0..f9c7d9a 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_display.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> > @@ -1003,6 +1003,12 @@ enum drm_mode_status
> dp_bridge_mode_valid(struct drm_bridge *bridge,
> >                 return -EINVAL;
> >         }
> >
> > +       if (dp->connector_type == DRM_MODE_CONNECTOR_eDP) {
> > +               if (mode_pclk_khz > DP_MAX_PIXEL_CLK_KHZ)
> > +                       return MODE_CLOCK_HIGH;
> > +               return MODE_OK;
> > +       }
> > +
> >         if ((dp->max_pclk_khz <= 0) ||
> >                         (dp->max_pclk_khz > DP_MAX_PIXEL_CLK_KHZ) ||
> >                         (mode->clock > dp->max_pclk_khz))
> > --
> > 2.7.4
> >
> 
> 
> --
> With best wishes
> Dmitry