linux-kernel - Re: [PATCH] drm/display: hdmi: Do not read EDID on disconnected connectors

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Message-ID: <2df6xkxqpljeowlqad6s5pxujefx6iw2a2caqlgljrgpmxlqqz@lark6bpzexca>
Date: Mon, 13 Jan 2025 11:16:32 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, kernel@...labora.com, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/display: hdmi: Do not read EDID on disconnected
 connectors

On Sat, Jan 11, 2025 at 12:04:09AM +0200, Cristian Ciocaltea wrote:
> The recently introduced hotplug event handler in the HDMI Connector
> framework attempts to unconditionally read the EDID data, leading to a
> bunch of non-harmful, yet quite annoying DDC/I2C related errors being
> reported.
> 
> Ensure the operation is performed only for connectors having the status
> connected or unknown.
> 
> Fixes: ab716b74dc9d ("drm/display/hdmi: implement hotplug functions")
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
> ---
>  drivers/gpu/drm/display/drm_hdmi_state_helper.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> index 2691e8b3e480131ac6e4e4b74b24947be55694bd..8e4b30e09b53b84cfd36199d56db3221a00085b0 100644
> --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> @@ -786,8 +786,10 @@ drm_atomic_helper_connector_hdmi_update(struct drm_connector *connector,
>  	const struct drm_edid *drm_edid;
>  
>  	if (status == connector_status_disconnected) {
> +		drm_edid_connector_update(connector, NULL);
>  		// TODO: also handle CEC and scramber, HDMI sink disconnected.
>  		drm_connector_hdmi_audio_plugged_notify(connector, false);
> +		return;

I think, it should be other way around: plugged_notify before
drm_edid_connector_update(). At least that would follow current logic of
the function.

>  	}
>  
>  	if (connector->hdmi.funcs->read_edid)
> 
> ---
> base-commit: 1854df7087be70ad54e24b2e308d7558ebea9f27
> change-id: 20250110-hdmi-conn-edid-read-fix-178513c2b7ea
> 

-- 
With best wishes
Dmitry