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

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Message-ID: <9faebd93-1c82-49e2-87f2-2928a016b044@collabora.com>
Date: Mon, 13 Jan 2025 13:39:02 +0200
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
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

Hi Dmitry,

On 1/13/25 11:16 AM, Dmitry Baryshkov wrote:
> 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.

Yeah, I wasn't really sure about the order here. Will get this fixed in v2.

Thanks,
Cristian