linux-kernel - Re: [PATCH v7] drm/msm/dp: reuse generic HDMI codec implementation

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Message-ID: <4E62D52FC6135E5B+a6b1634e-5c66-4db5-bb1e-bf64e2e8d8a2@radxa.com>
Date: Thu, 29 May 2025 10:40:12 +0800
From: Xilin Wu <sophon@...xa.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 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>,
 Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>,
 Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>,
 Hermes Wu <Hermes.wu@....com.tw>, Dmitry Baryshkov <lumag@...nel.org>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org
Subject: Re: [PATCH v7] drm/msm/dp: reuse generic HDMI codec implementation

On 2025/4/24 01:52:45, Dmitry Baryshkov wrote:
> From: Dmitry Baryshkov <lumag@...nel.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@...aro.org>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....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.

[    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.

-- 
Best regards,
Xilin Wu <sophon@...xa.com>