linux-kernel - Re: [PATCH v3] drm/bridge: sii902x: Fix HDMI detection with DRM_BRIDGE_ATTACH_NO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <734c8b32-a9a7-4fe5-a6d7-748770e502aa@ti.com>
Date: Thu, 9 Oct 2025 20:39:47 +0530
From: Devarsh Thakkar <devarsht@...com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
CC: <andrzej.hajda@...el.com>, <neil.armstrong@...aro.org>, <rfoss@...nel.org>,
        <airlied@...il.com>, <maarten.lankhorst@...ux.intel.com>,
        <mripard@...nel.org>, <tzimmermann@...e.de>,
        <dri-devel@...ts.freedesktop.org>, <jani.nikula@...el.com>,
        <simona@...ll.ch>, <linux-kernel@...r.kernel.org>,
        <tomi.valkeinen@...asonboard.com>, <praneeth@...com>,
        <vigneshr@...com>, <aradhya.bhatia@...ux.dev>, <s-jain1@...com>,
        <s-wang12@...com>, <r-donadkar@...com>, <h-shenoy@...com>
Subject: Re: [PATCH v3] drm/bridge: sii902x: Fix HDMI detection with
 DRM_BRIDGE_ATTACH_NO_CONNECTOR

Hi Dmitry,

Thanks for the quick reviews.

On 09/10/25 01:48, Dmitry Baryshkov wrote:
> On Tue, Oct 07, 2025 at 04:53:09PM +0530, Devarsh Thakkar wrote:
>> The SII902x HDMI bridge driver wasn't working properly with drivers that
>> use the newer bridge connector architecture with the
>> DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, like TIDSS.  This caused HDMI audio to
>> fail since the driver wasn't properly setting the sink_is_hdmi flag when
>> the bridge was attached without a connector since .get_modes() is never
>> called in this case. Fix it by setting sink_is_hdmi flag when reading
>> the EDID block itself.
>>
>> Fixes: 3de47e1309c2 ("drm/bridge: sii902x: use display info is_hdmi")
>> Signed-off-by: Devarsh Thakkar <devarsht@...com>
>> ---
>> V3: Use drm_edid_connector_update without edid NULL check
>> V2: Use drm_edid_connector_update to detect HDMI
>>
>> Link to V2:
>> https://lore.kernel.org/all/20251006150714.3144368-1-devarsht@ti.com/
>> Link to V1:
>> https://lore.kernel.org/all/20251003143642.4072918-1-devarsht@ti.com/
>>
>>   drivers/gpu/drm/bridge/sii902x.c | 5 ++---
>>   1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
>> index d537b1d036fb..bb613d4c281f 100644
>> --- a/drivers/gpu/drm/bridge/sii902x.c
>> +++ b/drivers/gpu/drm/bridge/sii902x.c
>> @@ -296,6 +296,8 @@ static const struct drm_edid *sii902x_edid_read(struct sii902x *sii902x,
>>   	mutex_lock(&sii902x->mutex);
>>   
>>   	drm_edid = drm_edid_read_ddc(connector, sii902x->i2cmux->adapter[0]);
>> +	drm_edid_connector_update(connector, drm_edid);
>> +	sii902x->sink_is_hdmi = connector->display_info.is_hdmi;
>>   
>>   	mutex_unlock(&sii902x->mutex);
>>   
>> @@ -309,14 +311,11 @@ static int sii902x_get_modes(struct drm_connector *connector)
>>   	int num = 0;
>>   
>>   	drm_edid = sii902x_edid_read(sii902x, connector);
>> -	drm_edid_connector_update(connector, drm_edid);
>>   	if (drm_edid) {
>>   		num = drm_edid_connector_add_modes(connector);
>>   		drm_edid_free(drm_edid);
>>   	}
> 
> The EDID read / free can also be dropped, they don't serve any purpose
> now.
> 

Sorry I did not understand this clearly.
I have already removed drm_edid_connector_update from sii902x_get_modes 
since now it is taken care inside sii902x_edid_read itself which is also 
called by .get_modes (sii902x_get_modes).

We still need to read edid inside sii902x_get_modes as for the legacy 
driver scenario which don't use DRM_BRIDGE_ATTACH_NO_CONNECTOR as in 
those cases .get_modes will get called but bridge function .edid_read 
won't be called. Also as the caller is supposed to free the edid 
allocated so I have preserved drm_edid_free call in .get_modes as 
drm_edid_connector_add_modes is allocating a new drm_edid pointer already.

Kindly let me know if there is a misunderstanding here.

Regards
Devarsh

>>   
>> -	sii902x->sink_is_hdmi = connector->display_info.is_hdmi;
>> -
>>   	return num;
>>   }
>>   
>> -- 
>> 2.39.1
>>
>