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From:   Hsin-Yi Wang <hsinyi@chromium.org>
Date:   Mon, 6 Nov 2023 12:38:26 -0800
Message-ID: <CAJMQK-gmu71-s_RoiWUAd_HHtJm_yN1YQ6+p+aQyKWKz1ACDsQ@mail.gmail.com>
Subject: Re: [PATCH v3 3/3] drm/panel-edp: Avoid adding multiple preferred modes
To:     Doug Anderson <dianders@chromium.org>
Cc:     Neil Armstrong <neil.armstrong@linaro.org>,
        Jessica Zhang <quic_jesszhan@quicinc.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
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On Mon, Nov 6, 2023 at 12:33=E2=80=AFPM Doug Anderson <dianders@chromium.or=
g> wrote:
>
> Hi,
>
> On Mon, Nov 6, 2023 at 12:27=E2=80=AFPM Hsin-Yi Wang <hsinyi@chromium.org=
> wrote:
> >
> > diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/=
panel-edp.c
> > index 0fb439b5efb1..54dbbdf62ec0 100644
> > --- a/drivers/gpu/drm/panel/panel-edp.c
> > +++ b/drivers/gpu/drm/panel/panel-edp.c
> > @@ -594,8 +594,20 @@ static int panel_edp_get_modes(struct drm_panel *p=
anel,
> >                                       p->detected_panel !=3D ERR_PTR(-E=
INVAL) &&
> >                                       p->detected_panel->override_edid_=
mode;
> >
> > -       /* probe EDID if a DDC bus is available */
> > -       if (p->ddc) {
> > +       /*
> > +        * If both edid and hard-coded modes exists, only add hard-code=
d modes
> > +        * to avoid multiple preferred modes.
> > +        */
> > +       if (p->desc->num_timings || p->desc->num_modes) {
> > +               /*
> > +                * Add hard-coded panel modes. Don't call this if there=
 are no
> > +                * timings and no modes (the generic edp-panel case) be=
cause it
> > +                * will clobber the display_info that was already set b=
y
> > +                * drm_add_edid_modes().
> > +                */
> > +               num +=3D panel_edp_get_non_edid_modes(p, connector);
> > +       } else if (p->ddc) {
> > +               /* probe EDID if a DDC bus is available */
>
> As per discussion in v2, I think if you have the "ddc" you still want
> to fetch the EDID, you just don't want to add the modes from the EDID.
> This will mean that the EDID is present in sysfs if userspace wants to
> look at it for whatever reason.
>
Ack. Will update this.

> -Doug