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

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Message-ID: <CAPY8ntDXJWR-vssSLsRbh7RTd-40SQApOxWGwt2LkeoyxCdYMw@mail.gmail.com>
Date:   Fri, 18 Dec 2020 14:21:18 +0000
From:   Dave Stevenson <dave.stevenson@...pberrypi.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Eric Anholt <eric@...olt.net>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Jason Cooper <jason@...edaemon.net>,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org,
        Marc Zyngier <maz@...nel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        LKML <linux-kernel@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-rpi-kernel@...ts.infradead.org,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Dom Cobley <popcornmix@...il.com>
Subject: Re: [PATCH 05/15] drm/vc4: hdmi: Restore cec physical address on reconnect

Hi  Maxime & Dom

On Thu, 10 Dec 2020 at 13:47, Maxime Ripard <maxime@...no.tech> wrote:
>
> From: Dom Cobley <popcornmix@...il.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@...il.com>
> Signed-off-by: Maxime Ripard <maxime@...no.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);
> +                               kfree(edid);
> +                       }
> +               }
>                 return connector_status_connected;
> +       }
>         cec_phys_addr_invalidate(vc4_hdmi->cec_adap);
>         return connector_status_disconnected;
>  }
> --
> 2.28.0
>