On Mon, Nov 19, 2018 at 09:19:34AM +0100, Maxime Ripard wrote:
> Hi,
>
> On Fri, Nov 16, 2018 at 07:18:29PM +0200, Priit Laes wrote:
> > From: Priit Laes <priit.laes@xxxxxxx>
> >
> > Even though HDMI connector features hotplug detect pin (HPD), there are
> > devices that which do not support it.
>
> Which devices?
Device I have here is labelled "AMATIC INDUSTRIES PT-MULTI-1" and
based on the TFP401APZP chip.
>
> > For these devices fall back to additional check on I2C bus. Of
> > course, there might be also devices that do not wire DDC pins too,
> > so we don't really know whether cable has been connected.
>
> Again, which devices?
OK, let's skip the part without DDC. I was probably thinking about
VGA cables when I was writing that..
> >
> > Signed-off-by: Priit Laes <plaes@xxxxxxxxx>
> > Signed-off-by: Priit Laes <priit.laes@xxxxxxx>
>
> You only need one :)
>
> > ---
> > drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 12 ++++++++----
> > 1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> > index 061d2e0d9011..bded09af1340 100644
> > --- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> > +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> > @@ -238,14 +238,18 @@ sun4i_hdmi_connector_detect(struct drm_connector *connector, bool force)
> > struct sun4i_hdmi *hdmi = drm_connector_to_sun4i_hdmi(connector);
> > unsigned long reg;
> >
> > - if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_HPD_REG, reg,
> > + if (!readl_poll_timeout(hdmi->base + SUN4I_HDMI_HPD_REG, reg,
> > reg & SUN4I_HDMI_HPD_HIGH,
> > 0, 500000)) {
> > - cec_phys_addr_invalidate(hdmi->cec_adap);
> > - return connector_status_disconnected;
> > + return connector_status_connected;
> > }
> >
> > - return connector_status_connected;
> > + if (!IS_ERR(hdmi->i2c) && drm_probe_ddc(hdmi->i2c))
> > + return connector_status_connected;
> > +
> > + cec_phys_addr_invalidate(hdmi->cec_adap);
> > +
> > + return connector_status_unknown;
>
> You're doing basically two things in that patch, first adding the
> fallback to the DDC probe if the hotplug mechanism couldn't detect the
> display, and then returning a status unknown if both fail.
Agreed. 'connector_status_disconnected' is the way to go.
> While I don't really have an opinion on the first one, it's mandatory
> for every HDMI device to be able to retrieve the EDID through the
> DDC. If a device was to disallow that, it would violate the HDMI, and
> I'm not sure we want to start supporting those devices.
Yes, Even if someone runs into those non-spec devices, then there's
also possibility to use the force argument.
Thanks for review!
>
> Maxime
>
> --
> Maxime Ripard, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
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