linux-kernel - Re: [PATCH v2] drm/gma500: replace drm_detect_hdmi_monitor() with drm_display_info.is

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Message-ID: <87o74ti7g5.fsf@intel.com>
Date: Thu, 12 Sep 2024 11:48:10 +0300
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: Thomas Zimmermann <tzimmermann@...e.de>, Tejas Vipin
 <tejasvipin76@...il.com>, Laurent.pinchart@...asonboard.com,
 patrik.r.jakobsson@...il.com, maarten.lankhorst@...ux.intel.com,
 mripard@...nel.org, airlied@...il.com, daniel@...ll.ch
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/gma500: replace drm_detect_hdmi_monitor() with
 drm_display_info.is_hdmi

On Thu, 12 Sep 2024, Thomas Zimmermann <tzimmermann@...e.de> wrote:
> Hi
>
> Am 11.09.24 um 20:06 schrieb Tejas Vipin:
>> Replace drm_detect_hdmi_monitor() with drm_display_info.is_hdmi since
>> monitor HDMI information is available after EDID is parsed. Additionally
>> rewrite the code the code to have fewer indentation levels.
>
> The problem is that the entire logic is outdated. The content 
> of cdv_hdmi_detect() should go into cdv_hdmi_get_modes(), the detect_ctx 
> callback should be set to drm_connector_helper_detect_from_ddc() and 
> cdv_hdmi_detect() should be deleted. The result is that ->detect_ctx 
> will detect the presence of a display and ->get_modes will update EDID 
> and other properties.

I guess I didn't get the memo on this one.

What's the problem with reading the EDID at detect? The subsequent
drm_edid_connector_add_modes() called from .get_modes() does not need to
read the EDID again.

I think it should be fine to do incremental refactors like the patch at
hand (modulo some issues I mention below).

BR,
Jani.


>
> Do you have  a device for testing such a change?
>
> Best regards
> Thomas
>
>>
>> Signed-off-by: Tejas Vipin <tejasvipin76@...il.com>
>> ---
>> Changes in v2:
>>      - Use drm_edid instead of edid
>>
>> Link to v1: https://lore.kernel.org/all/20240910051856.700210-1-tejasvipin76@gmail.com/
>> ---
>>   drivers/gpu/drm/gma500/cdv_intel_hdmi.c | 24 +++++++++++++-----------
>>   1 file changed, 13 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/gma500/cdv_intel_hdmi.c b/drivers/gpu/drm/gma500/cdv_intel_hdmi.c
>> index 2d95e0471291..701f8bbd5f2b 100644
>> --- a/drivers/gpu/drm/gma500/cdv_intel_hdmi.c
>> +++ b/drivers/gpu/drm/gma500/cdv_intel_hdmi.c
>> @@ -128,23 +128,25 @@ static enum drm_connector_status cdv_hdmi_detect(
>>   {
>>   	struct gma_encoder *gma_encoder = gma_attached_encoder(connector);
>>   	struct mid_intel_hdmi_priv *hdmi_priv = gma_encoder->dev_priv;
>> -	struct edid *edid = NULL;
>> +	const struct drm_edid *drm_edid;
>> +	int ret;
>>   	enum drm_connector_status status = connector_status_disconnected;
>>   
>> -	edid = drm_get_edid(connector, connector->ddc);
>> +	drm_edid = drm_edid_read_ddc(connector, connector->ddc);

Just drm_edid_read() is enough when you're using connector->ddc.

>> +	ret = drm_edid_connector_update(connector, drm_edid);
>>   
>>   	hdmi_priv->has_hdmi_sink = false;
>>   	hdmi_priv->has_hdmi_audio = false;
>> -	if (edid) {
>> -		if (edid->input & DRM_EDID_INPUT_DIGITAL) {
>> -			status = connector_status_connected;
>> -			hdmi_priv->has_hdmi_sink =
>> -						drm_detect_hdmi_monitor(edid);
>> -			hdmi_priv->has_hdmi_audio =
>> -						drm_detect_monitor_audio(edid);
>> -		}
>> -		kfree(edid);
>> +	if (ret)

This error path leaks the EDID.

>> +		return status;
>> +
>> +	if (drm_edid_is_digital(drm_edid)) {
>> +		status = connector_status_connected;
>> +		hdmi_priv->has_hdmi_sink = connector->display_info.is_hdmi;
>> +		hdmi_priv->has_hdmi_audio = connector->display_info.has_audio;
>>   	}
>> +	drm_edid_free(drm_edid);
>> +
>>   	return status;
>>   }
>>   

-- 
Jani Nikula, Intel