Re: [PATCH 05/15] drm/vc4: hdmi: Restore cec physical address on reconnect

[Maxime Ripard <maxime@cerno.tech>]

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Hi Dave,

Thanks for your review

On Fri, Dec 18, 2020 at 02:45:54PM +0000, Dave Stevenson wrote:
> On Fri, 18 Dec 2020 at 14:21, Dave Stevenson
> <dave.stevenson@raspberrypi.com> wrote:
> >
> > Hi  Maxime & Dom
> >
> > On Thu, 10 Dec 2020 at 13:47, Maxime Ripard <maxime@cerno.tech> wrote:
> > >
> > > From: Dom Cobley <popcornmix@gmail.com>
> > >
> > > Currently we call cec_phys_addr_invalidate on a hotplug deassert.
> > > That may be due to a TV power cycling, or an AVR being switched
> > > on (and switching edid).
> > >
> > > This makes CEC unusable since our controller wouldn't have a physical
> > > address anymore.
> > >
> > > Set it back up again on the hotplug assert.
> > >
> > > Fixes: 15b4511a4af6 ("drm/vc4: add HDMI CEC support")
> > > Signed-off-by: Dom Cobley <popcornmix@gmail.com>
> > > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> > > ---
> > >  drivers/gpu/drm/vc4/vc4_hdmi.c | 25 +++++++++++++++++--------
> > >  1 file changed, 17 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > > index 28b78ea885ea..eff3bac562c6 100644
> > > --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> > > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > > @@ -136,20 +136,29 @@ static enum drm_connector_status
> > >  vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
> > >  {
> > >         struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
> > > +       bool connected = false;
> > >
> > >         if (vc4_hdmi->hpd_gpio) {
> > >                 if (gpio_get_value_cansleep(vc4_hdmi->hpd_gpio) ^
> > >                     vc4_hdmi->hpd_active_low)
> > > -                       return connector_status_connected;
> > > -               cec_phys_addr_invalidate(vc4_hdmi->cec_adap);
> > > -               return connector_status_disconnected;
> > > -       }
> > > -
> > > -       if (drm_probe_ddc(vc4_hdmi->ddc))
> > > -               return connector_status_connected;
> > > -
> > > +                       connected = true;
> > > +       } else if (drm_probe_ddc(vc4_hdmi->ddc))
> > > +               connected = true;
> > >         if (HDMI_READ(HDMI_HOTPLUG) & VC4_HDMI_HOTPLUG_CONNECTED)
> >
> > This needs to become an "else if(...".
> > It used to be that all the other paths would return, so were mutually
> > exclusive to this. Now they set a thing and keep going we need to
> > avoid reading the register should there be a HPD gpio or the ddc probe
> > succeeds.
> > Memory says that otherwise Pi3 always reports connected.
> >
> > I fixed this in a downstream patch already -
> > https://github.com/raspberrypi/linux/commit/d345caec1e9b2317b9cd7eb5b92ae453a0d3e98c
> >
> > Otherwise fine.
> >
> >   Dave
> >
> > > +               connected = true;
> > > +       if (connected) {
> > > +               if (connector->status != connector_status_connected) {
> > > +                       struct edid *edid = drm_get_edid(connector, vc4_hdmi->ddc);
> > > +
> > > +                       if (edid) {
> > > +                               cec_s_phys_addr_from_edid(vc4_hdmi->cec_adap, edid);
> > > +                               vc4_hdmi->encoder.hdmi_monitor = drm_detect_hdmi_monitor(edid);
> > > +                               drm_connector_update_edid_property(connector, edid);
> 
> Actually looking at this again in the context of the other changes, do
> we need to call drm_connector_update_edid_property() here?
> 
> We've just called drm_get_edid() to get the edid, and that calls
> drm_connector_update_edid_property() as well [1]

Yeah, you're right I'll drop it

> Updating vc4_hdmi->encoder.hdmi_monitor may be necessary. It's
> otherwise done in vc4_hdmi_connector_get_modes, which I sort of expect
> to be called almost immediately by the framework when connector_detect
> returns "connected". I haven't checked if that is guaranteed though.
> 
> vc4_hdmi_connector_get_modes also includes a manual call to
> drm_connector_update_edid_property after having just called
> drm_get_edid, so that one feels redundant too.

.get_modes is called in drm_helper_probe_single_connector_modes, which
is usually the helper set in .fill_modes. .fill_modes seems to only be
called when either DRM_IOCTL_MODE_GETCONNECTOR is called, or when the
connector status is forced through sysfs, so it doesn't look like it's
done automatically.

I'm not sure we need to set hdmi_monitor though, it's only used to
configure the display related side, and that can't happen without
get_modes being called.

Maxime

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