linux-kernel - Re: [PATCH v2 05/15] drm/vc4: hdmi: Restore cec physical address on reconnect

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Message-ID: <CAPY8ntD=52HEwc6-3XggH4_CErjc2q9aBUc_c29L13UGuJcvqQ@mail.gmail.com>
Date:   Fri, 22 Jan 2021 10:31:53 +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>,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        LKML <linux-kernel@...r.kernel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        bcm-kernel-feedback-list@...adcom.com,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Dom Cobley <popcornmix@...il.com>
Subject: Re: [PATCH v2 05/15] drm/vc4: hdmi: Restore cec physical address on reconnect

Hi Maxime

Sorry for the slow reply on these patches.

On Mon, 11 Jan 2021 at 14:23, 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>

I follow the logic, and trust Dom that it works, but I don't know if
that is the correct thing within CEC.
Ideally Hans will comment as the original author of the CEC code - I
believe he's testing the series anyway.

Acked-by: Dave Stevenson <dave.stevenson@...pberrypi.com>

> ---
>  drivers/gpu/drm/vc4/vc4_hdmi.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 7945dbcee78c..c3a301396aad 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -136,20 +136,32 @@ 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;
> +                       connected = true;
> +       } else if (drm_probe_ddc(vc4_hdmi->ddc)) {
> +               connected = true;
> +       } else if (HDMI_READ(HDMI_HOTPLUG) & VC4_HDMI_HOTPLUG_CONNECTED) {
> +               connected = true;
>         }
>
> -       if (drm_probe_ddc(vc4_hdmi->ddc))
> -               return connector_status_connected;
> +       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);
> +                               kfree(edid);
> +                       }
> +               }
>
> -       if (HDMI_READ(HDMI_HOTPLUG) & VC4_HDMI_HOTPLUG_CONNECTED)
>                 return connector_status_connected;
> +       }
> +
>         cec_phys_addr_invalidate(vc4_hdmi->cec_adap);
>         return connector_status_disconnected;
>  }
> --
> 2.29.2
>