linux-kernel - Re: [PATCH 5.15 247/779] drm/meson: encoder_hdmi: switch to bridge DRM_BRIDGE_ATTACH_NO

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Date:   Fri, 23 Sep 2022 11:12:02 +0200
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Stefan Agner <stefan@...er.ch>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Sam Ravnborg <sam@...nborg.org>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Sasha Levin <sashal@...nel.org>,
        linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH 5.15 247/779] drm/meson: encoder_hdmi: switch to bridge
 DRM_BRIDGE_ATTACH_NO_CONNECTOR

Hi Greg,

On 13/09/2022 13:22, Greg Kroah-Hartman wrote:
> On Mon, Sep 12, 2022 at 08:48:24PM +0200, Stefan Agner wrote:
>> On 2022-09-12 18:08, Stefan Agner wrote:
>>> On 2022-08-15 19:58, Greg Kroah-Hartman wrote:
>>>> From: Neil Armstrong <narmstrong@...libre.com>
>>>>
>>>> [ Upstream commit 0af5e0b41110e2da872030395231ab19c45be931 ]
>>>>
>>>> This implements the necessary change to no more use the embedded
>>>> connector in dw-hdmi and use the dedicated bridge connector driver
>>>> by passing DRM_BRIDGE_ATTACH_NO_CONNECTOR to the bridge attach call.
>>>>
>>>> The necessary connector properties are added to handle the same
>>>> functionalities as the embedded dw-hdmi connector, i.e. the HDR
>>>> metadata, the CEC notifier & other flags.
>>>>
>>>> The dw-hdmi output_port is set to 1 in order to look for a connector
>>>> next bridge in order to get DRM_BRIDGE_ATTACH_NO_CONNECTOR working.
>>>
>>> HDMI on ODROID-N2+ was working with v5.15.60, and stopped working with
>>> v5.15.61. Reverting this commit (and two dependent refcount leak) to be
>>> the culprit. Reverting just the refcount leaks is not enough to get HDMI
>>> working, so I assume it is this commit.
>>>
>>> I haven't investigated much beyond that, maybe its simple a case of a
>>> missing kernel configuration? DRM_DISPLAY_CONNECTOR is compiled, and the
>>> module display_connector is loaded, so that part seemed to have worked.
>>>
>>> Any ideas welcome.
>>>
>>> FWIW, I track the issue in the HAOS tracker at
>>> https://github.com/home-assistant/operating-system/issues/2120.
>>
>> It seems that backporting commit 7cd70656d128 ("drm/bridge:
>> display-connector: implement bus fmts callbacks") fixes the problem
>> without reverting this commit.
>>
>> @Greg, can we backport this commit as well?
> 
> sure, now queued up, thanks.

Backport of 7cd70656d128 ("drm/bridge: display-connector: implement bus fmts callbacks") is still missing in 5.15-stable.

Thanks,
Neil

> 
> greg k-h
>