linux-kernel - Re: [PATCH v2] drm/display: add hw_params callback function to drm_connector_hdmi_audio

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: <rydatk4grelhg6w57wwkqafq5ghccnsuiwvfqvvdv7qum5dg5a@scoc76ni7hue>
Date: Fri, 26 Sep 2025 18:09:15 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Srinivas Kandagatla <srini@...nel.org>
Cc: Jianfeng Liu <liujianfeng1994@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
        linux-arm-msm@...r.kernel.org, Xilin Wu <sophon@...xa.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        David Airlie <airlied@...il.com>, Dmitry Baryshkov <lumag@...nel.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>, Simona Vetter <simona@...ll.ch>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-sound@...r.kernel.org
Subject: Re: [PATCH v2] drm/display: add hw_params callback function to
 drm_connector_hdmi_audio_ops

On Fri, Sep 26, 2025 at 11:30:26AM +0100, Srinivas Kandagatla wrote:
> 
> 
> On 9/25/25 5:28 AM, Dmitry Baryshkov wrote:
> > On Thu, Sep 25, 2025 at 12:05:09PM +0800, Jianfeng Liu wrote:
> >> After reusing drm_hdmi_audio_* helpers and drm_bridge_connector
> >> integration in drm/msm/dp, we have dropped msm_dp_audio_hw_params and
> >> use msm_dp_audio_prepare instead. While userspace is still calling
> >> hw_params to do audio initialization, and we get the following errors:
> >>
> >> q6apm-lpass-dais 3700000.remoteproc:glink-edge:gpr:service@1:bedais: q6apm_lpass_dai_prepare() started
> >> q6apm-lpass-dais 3700000.remoteproc:glink-edge:gpr:service@1:bedais: q6apm_lpass_dai_prepare() started
> >> q6apm-lpass-dais 3700000.remoteproc:glink-edge:gpr:service@1:bedais: q6apm_lpass_dai_prepare() started
> >> hdmi-audio-codec hdmi-audio-codec.0.auto: hdmi_codec_hw_params() started
> >> q6apm-lpass-dais 3700000.remoteproc:glink-edge:gpr:service@1:bedais: q6apm_lpass_dai_prepare() started
> >> qcom-apm gprsvc:service:2:1: Error (1) Processing 0x01001002 cmd
> >> qcom-apm gprsvc:service:2:1: DSP returned error[1001002] 1
> >> q6apm-lpass-dais 3700000.remoteproc:glink-edge:gpr:service@1:bedais: Failed to start APM port 104
> >> q6apm-lpass-dais 3700000.remoteproc:glink-edge:gpr:service@1:bedais: ASoC error (-22): at snd_soc_dai_prepare() on DISPLAY_PORT_RX_0
> >> MultiMedia2 Playback: ASoC error (-22): at dpcm_run_update_startup() on MultiMedia2 Playback
> > 
> > And a call to hdmi_codec_prepare() comes only at this place.
> > 
> > Srini, Mark, when selecting to only implement .prepare for codec ops I
> > was following the commit 2fef64eec23a ("ASoC: hdmi-codec: Add a prepare
> > hook"), which documents that IEC958 status bit is set after
> > .hw_params(), so it's only visible during .prepare(). Is it okay to
> > implement both callbacks? Or should the audioreach DAI driver be fixed
> > somehow instead (I suppose it assumes that the port is available after
> > .hw_params(), not sure if that assumption is correct)?
> > 
> >>
> >> msm_dp_audio_prepare is not called because hdmi-codec driver only checks
> >> and runs hw_params before q6apm_lpass_dai_prepare(). This commit will
> >> add hw_params callback same as drm_connector_hdmi_audio_prepare, so that
> >> hdmi-codec driver can work with userspace alsa.
> >>
> >> Tested with Radxa Dragon Q6A.
> >>
> >> Fixes: 98a8920e7b07 ("drm/msm/dp: reuse generic HDMI codec implementation")
> >> Signed-off-by: Jianfeng Liu <liujianfeng1994@...il.com>
> > 
> > The patch LGTM, but I would wait for response from audio maintainers.
> > 
> 
> The ordering matters in this case as we need clocks and audio
> configuration on DP codec side to be setup before we start configuring
> the dsp pipeline. Looks like that DSP is trying to setup DP endpoint
> even before it is ready.
> 
> q6apm prepare loads the dsp pipeline and starts configuring the
> endpoints, if the DP endpoint is not ready dsp would throw an error.
> 
> We might be able to pull in some dsp logs to confirm this, but I dont
> have a setup that I can reproduce this issue.

What would be your recommendation to proceed? Is it okay for the DAI
driver to depend on the .hw_params enabling the clock? Also I see that
the error regarding the clocks comes from .prepare callback too. What is
the order of .prepare callbacks()? Can we influence it?

> 
> 
> --srini
> >> ---
> >>
> >> Changes in v2:
> >> - Link to v1: https://lore.kernel.org/linux-arm-msm/20250924085804.34183-1-liujianfeng1994@gmail.com/
> >> - Use more detailed trace log in commit message.
> >> - Drop the empty line between Fixex and SoB.
> >>
> >>  drivers/gpu/drm/display/drm_hdmi_audio_helper.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/drivers/gpu/drm/display/drm_hdmi_audio_helper.c b/drivers/gpu/drm/display/drm_hdmi_audio_helper.c
> >> index 7d78b02c1446..6ca1c7ad0632 100644
> >> --- a/drivers/gpu/drm/display/drm_hdmi_audio_helper.c
> >> +++ b/drivers/gpu/drm/display/drm_hdmi_audio_helper.c
> >> @@ -130,6 +130,7 @@ EXPORT_SYMBOL(drm_connector_hdmi_audio_plugged_notify);
> >>  
> >>  static const struct hdmi_codec_ops drm_connector_hdmi_audio_ops = {
> >>  	.audio_startup = drm_connector_hdmi_audio_startup,
> >> +	.hw_params = drm_connector_hdmi_audio_prepare,
> >>  	.prepare = drm_connector_hdmi_audio_prepare,
> >>  	.audio_shutdown = drm_connector_hdmi_audio_shutdown,
> >>  	.mute_stream = drm_connector_hdmi_audio_mute_stream,
> >> -- 
> >> 2.43.0
> >>
> > 
> 

-- 
With best wishes
Dmitry