linux-kernel - Re: [PATCH v2 1/3] drm/msm/dp: check sink_count before update is

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Message-ID: <161843513989.46595.8623474483864386727@swboyd.mtv.corp.google.com>
Date:   Wed, 14 Apr 2021 14:18:59 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Kuogee Hsieh <khsieh@...eaurora.org>, robdclark@...il.com,
        sean@...rly.run
Cc:     tanmay@...eaurora.org, abhinavk@...eaurora.org,
        aravindh@...eaurora.org, khsieh@...eaurora.org, airlied@...ux.ie,
        daniel@...ll.ch, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] drm/msm/dp: check sink_count before update is_connected status

Quoting Kuogee Hsieh (2021-04-14 14:02:34)
> Link status is different from display connected status in the case
> of something like an Apple dongle where the type-c plug can be
> connected, and therefore the link is connected, but no sink is
> connected until an HDMI cable is plugged into the dongle.
> The sink_count of DPCD of dongle will increase to 1 once an HDMI
> cable is plugged into the dongle so that display connected status
> will become true. This checking also apply at pm_resume.
> 
> Fixes: 94e58e2d06e3 ("drm/msm/dp: reset dp controller only at boot up and pm_resume")
> Reported-by: Stephen Boyd <swboyd@...omium.org>
> Reviewed-by: Stephen Boyd <swboyd@...omium.org>
> Tested-by: Stephen Boyd <swboyd@...omium.org>
> Signed-off-by: Kuogee Hsieh <khsieh@...eaurora.org>
> ---

Can you please thread your emailed patches? I see them all as toplevel
messages in my inbox :(


>  drivers/gpu/drm/msm/dp/dp_display.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 5a39da6..0ba71c7 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -586,10 +586,8 @@ static int dp_connect_pending_timeout(struct dp_display_private *dp, u32 data)
>         mutex_lock(&dp->event_mutex);
>  
>         state = dp->hpd_state;
> -       if (state == ST_CONNECT_PENDING) {
> -               dp_display_enable(dp, 0);
> +       if (state == ST_CONNECT_PENDING)
>                 dp->hpd_state = ST_CONNECTED;
> -       }
>  
>         mutex_unlock(&dp->event_mutex);
>  
> @@ -669,10 +667,8 @@ static int dp_disconnect_pending_timeout(struct dp_display_private *dp, u32 data
>         mutex_lock(&dp->event_mutex);
>  
>         state =  dp->hpd_state;
> -       if (state == ST_DISCONNECT_PENDING) {
> -               dp_display_disable(dp, 0);
> +       if (state == ST_DISCONNECT_PENDING)
>                 dp->hpd_state = ST_DISCONNECTED;
> -       }
>  
>         mutex_unlock(&dp->event_mutex);
>  
> @@ -1272,7 +1268,12 @@ static int dp_pm_resume(struct device *dev)
>  
>         status = dp_catalog_link_is_connected(dp->catalog);
>  
> -       if (status)
> +       /*
> +        * can not declared display is connected unless
> +        * HDMI cable is plugged in and sink_count of
> +        * dongle become 1
> +        */
> +       if (status && dp->link->sink_count)
>                 dp->dp_display.is_connected = true;
>         else
>                 dp->dp_display.is_connected = false;

With this patch applied things still go wrong for me sometimes. I can
connect the apple dongle and then disconnect the apple dongle, instead
of connect and disconnect the HDMI cable, and sometimes the external
display doesn't come on. I'm still investigating but just wanted to let
you know.