linux-kernel - Re: [PATCH v3 2/2] drm/msm/dp: Implement oob_hotplug

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Date:   Fri, 22 Apr 2022 21:12:16 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        Rob Clark <robdclark@...il.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Sean Paul <sean@...rly.run>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Stephen Boyd <swboyd@...omium.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        intel-gfx@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v3 2/2] drm/msm/dp: Implement oob_hotplug_event()

On Fri 22 Apr 16:07 PDT 2022, Dmitry Baryshkov wrote:
> On 23/04/2022 01:32, Bjorn Andersson wrote:
[..]
> > diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
> > index 80f59cf99089..76904b1601b1 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_drm.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_drm.c
> > @@ -123,6 +123,14 @@ static enum drm_mode_status dp_connector_mode_valid(
> >   	return dp_display_validate_mode(dp_disp, mode->clock);
> >   }
> > +static void dp_oob_hotplug_event(struct drm_connector *connector,
> > +				 enum drm_connector_hpd_state hpd_state)
> > +{
> > +	struct msm_dp *dp_disp = to_dp_connector(connector)->dp_display;
> > +
> > +	dp_display_oob_hotplug_event(dp_disp, hpd_state);
> > +}
> > +
> >   static const struct drm_connector_funcs dp_connector_funcs = {
> >   	.detect = dp_connector_detect,
> >   	.fill_modes = drm_helper_probe_single_connector_modes,
> > @@ -130,6 +138,7 @@ static const struct drm_connector_funcs dp_connector_funcs = {
> >   	.reset = drm_atomic_helper_connector_reset,
> >   	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> >   	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> > +	.oob_hotplug_event = dp_oob_hotplug_event,
> 
> We were (are) going to switch dp driver to use drm_bridge_connector (to fix
> support for bridge chains, eDP panels, etc.
> 
> So these changes must be ported to drm_bridge_connector (or we must
> abandon/defer the idea of using the bridge_connector).
> 
> For the oob_hotplug_event() callback proper support might be as simple as
> calling drm_bridge_connector_hpd_cb().
> 

Are you saying that you have code ready and being merged into linux-next
that I should redesign this on top of, or that you're planning to write
some code in the future and DisplayPort support have to wait until then?

> >   };
> >   static const struct drm_connector_helper_funcs dp_connector_helper_funcs = {
> > @@ -160,6 +169,8 @@ struct drm_connector *dp_drm_connector_init(struct msm_dp *dp_display)
> >   	if (ret)
> >   		return ERR_PTR(ret);
> > +	connector->fwnode = fwnode_handle_get(dev_fwnode(dp_display->dev));
> > +
> 
> This would be much more interesting. Supporting this in a generic way might
> be tricky. But we can still set the fwnode manually from the dp code.
> 

There's a slight mishmash here, because the device used to initialize
the connector is the drm_dev, but we need the actual fwnode of the DP
device associated with the connector.

So I think this is how it needs to be done.

Regards,
Bjorn