Message-ID: <7vtf5dlfvwkhms7c6licxf6hw3653uckv2trqjmy5sfl33lbuy@565k4iqcvwhg>
Date: Thu, 23 Oct 2025 16:21:43 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Srinivas Kandagatla <srinivas.kandagatla@....qualcomm.com>
Cc: Srinivas Kandagatla <srini@...nel.org>,
        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>,
        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,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: Re: [PATCH v2] drm/display: add hw_params callback function to
 drm_connector_hdmi_audio_ops

On Thu, Oct 23, 2025 at 01:47:33PM +0100, Srinivas Kandagatla wrote:
> 
> 
> On 10/23/25 1:24 PM, Dmitry Baryshkov wrote:
> > On Thu, Oct 23, 2025 at 12:48:59PM +0100, Srinivas Kandagatla wrote:
> >>
> >>
> >> On 10/23/25 12:43 PM, Dmitry Baryshkov wrote:
> >>> On Sun, Oct 05, 2025 at 06:29:20PM +0300, Dmitry Baryshkov wrote:
> >>>> On Sat, Oct 04, 2025 at 02:16:08PM +0100, Srinivas Kandagatla wrote:
> >>>>>
> >>>>>
> >>>>> On 10/3/25 6:02 PM, Dmitry Baryshkov wrote:
> >>>>>> On Fri, Oct 03, 2025 at 05:35:16PM +0100, Srinivas Kandagatla wrote:
> >>>>>>>
> >>>>>>>
> >>>>>>> On 9/26/25 4:09 PM, Dmitry Baryshkov wrote:
> >>>>>>>> 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?
> >>>>>>>
> >>>>>>> prepare follows hw-params, and prepare can be called multiple times
> >>>>>>>
> >>>>>>> When you mean order of prepare callbacks, you mean w.r.t codec and dsp
> >>>>>>> backend dia link drivers ?
> >>>>>>
> >>>>>> Yes. Here we got a dependency from the cpu dai to be prepare()'d after
> >>>>>> the DP driver performs some actions, which were a part of hw_params()
> >>>>>> callback but were moved to be executed during prepare() callback.
> >>>>>>
> >>>>>> This leads me to two sets of questions:
> >>>>>> - In which order are those callbacks executed? Can we make the ASoC
> >>>>>>   enforce some order of DAI's prepare() callbacks?
> >>>>>>
> >>>>>> - More improtantly, isn't it a sympthom of DP driver (incorrectly)
> >>>>>>   performing too much in the .hw_params() / .prepare() callback? Should
> >>>>>>   we move some of the setup to the .audio_startup() instead? What is the
> >>>>>>   expected split between those callbacks?
> >>>>>
> >>>>> I have not looked at full dp sequences but, if prepare is the only place
> >>>>> when it enables the required clocks for audio block, then it is a
> >>>>> problem, we should do it early so that DSP can enable the required
> >>>>> configuration in prepare.
> >>>>
> >>>> As I wrote, previously it was done as a part of hw_params, which is
> >>>> also not optimal as hdmi-codec clearly defines both callbacks as
> >>>> optional, requiring only one of them. Do you know, what is actually
> >>>> required on the DP side for the DSP to be able to preapre()?
> >>>
> >>> Srinivas, did you have a chance to look at this? Or the .hw_prepare
> >>> ordering? I really don't want to land this fix only to face the same
> >>> issue because on some of the platforms .hw_prepare() callbacks will be
> >>> called in a different order.
> >>>
> >> Dmitry, few days back Krzysztof was enabling DP audio on T14s, and we
> >> have seen that the DSP is not happy and returning error 1 when we try to
> >> prepare the dp port. The exact reason is codec is not ready at that point.
> >>
> >>
> >> By adding this patch, Krzystof managed to get DP working.
> >> XElite platforms were working before 2fef64eec23a ("ASoC: hdmi-codec:
> >> Add a prepare) patch was merged, basically 2fef64eec23a broke what was
> >> working before.
> >>
> >> Am happy with this patch, better move to hw_params instead of prepare.
> > 
> > And I'm not happy with it :-)
> > 
> > hdmi-codec defines that one of the callbacks can be optional. We know
> > that at .hw_params time we don't have IEC 958 status bits, so we will be
> > programming incorrect audioframe.
> Your statement is contradicting with callbacks that are supported by
> hdmi-codec.
> 
> hdmi-codec uses IEC 958 status bits both in hw_params and prepare, if
> hw_params is not the right place, then that should be clarified and not
> correct for any of the codec drivers to use this callback.>

See https://lore.kernel.org/all/20210525132354.297468-6-maxime@cerno.tech/

> > Should some bits of code be moved to .audio_enable isntead? If so, which
> > bits?
> 
> I have not read the data sheet of msm dp block yet, but what it looks to
> me is the audio engine in the DP is powered off while dsp is trying to
> set it up.

Okay. What exactly is expected by the DSP? Which part, signal or clock
should be on?

-- 
With best wishes
Dmitry

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