[PATCH v7] drm/msm/dp: reuse generic HDMI codec implementation

[Xilin Wu]

On 2025/6/3 22:06:36, Dmitry Baryshkov wrote:
> On Thu, May 29, 2025 at 10:40:12AM +0800, Xilin Wu wrote:
>> On 2025/4/24 01:52:45, Dmitry Baryshkov wrote:
>>> From: Dmitry Baryshkov <lumag at kernel.org>
>>>
>>> The MSM DisplayPort driver implements several HDMI codec functions
>>> in the driver, e.g. it manually manages HDMI codec device registration,
>>> returning ELD and plugged_cb support. In order to reduce code
>>> duplication reuse drm_hdmi_audio_* helpers and drm_bridge_connector
>>> integration.
>>>
>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at oss.qualcomm.com>
>>> ---
>>> A lot of DisplayPort bridges use HDMI Codec in order to provide audio
>>> support. Present DRM HDMI Audio support has been written with the HDMI
>>> and in particular DRM HDMI Connector framework support, however those
>>> audio helpers can be easily reused for DisplayPort drivers too.
>>>
>>> Patches by Hermes Wu that targeted implementing HDMI Audio support in
>>> the iTE IT6506 driver pointed out the necessity of allowing one to use
>>> generic audio helpers for DisplayPort drivers, as otherwise each driver
>>> has to manually (and correctly) implement the get_eld() and plugged_cb
>>> support.
>>>
>>> Implement necessary integration in drm_bridge_connector and provide an
>>> example implementation in the msm/dp driver.
>>> ---
>>> Changes in v7:
>>> - Dropped applied patches
>>> - Link to v6: https://lore.kernel.org/r/20250314-dp-hdmi-audio-v6-0-dbd228fa73d7@oss.qualcomm.com
>>>
>>> Changes in v6:
>>> - Added DRM_BRIDGE_OP_DP_AUDIO and separate set of DisplayPort audio
>>>     callbacks to the drm_bridge interface (Maxime)
>>> - Link to v5: https://lore.kernel.org/r/20250307-dp-hdmi-audio-v5-0-f3be215fdb78@linaro.org
>>>
>>> Changes in v5:
>>> - Rebased on top of linux-next, also handling HDMI audio piece of the
>>>     MSM HDMI driver.
>>> - Link to v4: https://lore.kernel.org/r/20250301-dp-hdmi-audio-v4-0-82739daf28cc@linaro.org
>>>
>>> Changes in v4:
>>> - Rebased on linux-next, adding DRM_BRIDGE_OP_HDMI_AUDIO to Synopsys QP
>>>     HDMI driver.
>>> - Drop outdated comment regarding subconnector from the commit message.
>>> - Link to v3: https://lore.kernel.org/r/20250219-dp-hdmi-audio-v3-0-42900f034b40@linaro.org
>>>
>>> Changes in v3:
>>> - Dropped DRM_BRIDGE_OP_DisplayPort, added DRM_BRIDGE_OP_HDMI_AUDIO
>>>     (Laurent, Maxime)
>>> - Dropped the subconnector patch (again)
>>> - Link to v2: https://lore.kernel.org/r/20250209-dp-hdmi-audio-v2-0-16db6ebf22ff@linaro.org
>>>
>>> Changes in v2:
>>> - Added drm_connector_attach_dp_subconnector_property() patches
>>> - Link to v1: https://lore.kernel.org/r/20250206-dp-hdmi-audio-v1-0-8aa14a8c0d4d@linaro.org
>>> ---
>>>    drivers/gpu/drm/msm/Kconfig         |   1 +
>>>    drivers/gpu/drm/msm/dp/dp_audio.c   | 131 ++++--------------------------------
>>>    drivers/gpu/drm/msm/dp/dp_audio.h   |  27 ++------
>>>    drivers/gpu/drm/msm/dp/dp_display.c |  28 ++------
>>>    drivers/gpu/drm/msm/dp/dp_display.h |   6 --
>>>    drivers/gpu/drm/msm/dp/dp_drm.c     |   8 +++
>>>    6 files changed, 31 insertions(+), 170 deletions(-)
>>>
>>
>> This change breaks DP audio on the qcs6490 platform, tested on kernel
>> next-20250528.
> 
> I can not confirm this issue here (though I tested it on a different
> hardware). Do you have any patches on top of linux-next?
> 

I have this patch series applied, but I don't think it could be relevant:

[PATCH v4 0/8] Enable audio on qcs6490-RB3Gen2 and qcm6490-idp boards
https://lore.kernel.org/all/20250527111227.2318021-1-quic_pkumpatl@quicinc.com/

>>
>> [    0.368035] [drm:dpu_kms_hw_init:1173] dpu hardware revision:0x70020000
>> [    0.369359] hdmi-audio-codec hdmi-audio-codec.0.auto: hdmi_codec_probe:
>> dai_count 0
>> [    0.369362] hdmi-audio-codec hdmi-audio-codec.0.auto: hdmi_codec_probe:
>> Missing hw_params
>> [    0.369364] hdmi-audio-codec hdmi-audio-codec.0.auto: hdmi_codec_probe:
>> Invalid parameters
>> [    0.369366] hdmi-audio-codec hdmi-audio-codec.0.auto: probe with driver
>> hdmi-audio-codec failed with error -22
>> [    0.370536] [drm] Initialized msm 1.12.0 for ae01000.display-controller
>> on minor 0
>>
>> Manually reverting this change solves the problem.
> 
> It is suspicious, since dai_count can not be 0. We set
> hdmi_audio_max_i2s_playback_channels to 8, which in turn should set the
> hdmi_codec_pdata.i2s to 1.
> 

It suddenly comes to my mind that I'm using a kernel with everything 
compiled as builtin. Could that be a possible issue?


-- 
Best regards,
Xilin Wu <sophon at radxa.com>