Re: [alsa-devel] [PATCH v4 2/2] soundwire: qcom: add support for SoundWire controller

[Srinivas Kandagatla]

Thanks Pierre for reviewing this!

On 30/10/2019 16:28, Pierre-Louis Bossart wrote:
> On 10/30/19 10:31 AM, Srinivas Kandagatla wrote:
> > Qualcomm SoundWire Master controller is present in most Qualcomm SoCs
> > either integrated as part of WCD audio codecs via slimbus or
> > as part of SOC I/O.
> >
> > This patchset adds support to a very basic controller which has been
> > tested with WCD934x SoundWire controller connected to WSA881x smart
> > speaker amplifiers.
>
> Sorry for the delay in reviewing this patch.
>
> I have a set of comments mostly on error handling and mapping between 
> ASoC callbacks and stream states (which took a lot of work on our side 
> and required an updated state machine in the patches shared last week).
>
> [snip]
>
> > +static int qcom_swrm_cmd_fifo_wr_cmd(struct qcom_swrm_ctrl *ctrl, u8 
> > cmd_data,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u8 dev_addr, u16 reg_addr)
> > +{
> > +ÂÂÂ DECLARE_COMPLETION_ONSTACK(comp);
> > +ÂÂÂ unsigned long flags;
> > +ÂÂÂ u32 val;
> > +ÂÂÂ int ret;
> > +
> > +ÂÂÂ spin_lock_irqsave(&ctrl->comp_lock, flags);
> > +ÂÂÂ ctrl->comp = ∁
> > +ÂÂÂ spin_unlock_irqrestore(&ctrl->comp_lock, flags);
> > +ÂÂÂ val = SWRM_REG_VAL_PACK(cmd_data, dev_addr,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ SWRM_SPECIAL_CMD_ID, reg_addr);
> > +ÂÂÂ ret = ctrl->reg_write(ctrl, SWRM_CMD_FIFO_WR_CMD, val);
> > +ÂÂÂ if (ret)
> > +ÂÂÂÂÂÂÂ goto err;
> > +
> > +ÂÂÂ ret = wait_for_completion_timeout(ctrl->comp,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ msecs_to_jiffies(TIMEOUT_MS));
> > +
> > +ÂÂÂ if (!ret)
> > +ÂÂÂÂÂÂÂ ret = SDW_CMD_IGNORED;
> > +ÂÂÂ else
> > +ÂÂÂÂÂÂÂ ret = SDW_CMD_OK;
> > +err:
> > +ÂÂÂ spin_lock_irqsave(&ctrl->comp_lock, flags);
> > +ÂÂÂ ctrl->comp = NULL;
> > +ÂÂÂ spin_unlock_irqrestore(&ctrl->comp_lock, flags);
> > +
> > +ÂÂÂ return ret;
> > +}
> > +
> > +static int qcom_swrm_cmd_fifo_rd_cmd(struct qcom_swrm_ctrl *ctrl,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u8 dev_addr, u16 reg_addr,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u32 len, u8 *rval)
> > +{
> > +ÂÂÂ int i, ret;
> > +ÂÂÂ u32 val;
> > +ÂÂÂ DECLARE_COMPLETION_ONSTACK(comp);
> > +ÂÂÂ unsigned long flags;
> > +
> > +ÂÂÂ spin_lock_irqsave(&ctrl->comp_lock, flags);
> > +ÂÂÂ ctrl->comp = ∁
> > +ÂÂÂ spin_unlock_irqrestore(&ctrl->comp_lock, flags);
> > +
> > +ÂÂÂ val = SWRM_REG_VAL_PACK(len, dev_addr, SWRM_SPECIAL_CMD_ID, 
> > reg_addr);
> > +ÂÂÂ ret = ctrl->reg_write(ctrl, SWRM_CMD_FIFO_RD_CMD, val);
> > +ÂÂÂ if (ret)
> > +ÂÂÂÂÂÂÂ goto err;
> > +
> > +ÂÂÂ ret = wait_for_completion_timeout(ctrl->comp,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ msecs_to_jiffies(TIMEOUT_MS));
> > +
> > +ÂÂÂ if (!ret) {
> > +ÂÂÂÂÂÂÂ ret = SDW_CMD_IGNORED;
> > +ÂÂÂÂÂÂÂ goto err;
> > +ÂÂÂ } else {
> > +ÂÂÂÂÂÂÂ ret = SDW_CMD_OK;
> > +ÂÂÂ }
> > +
> > +ÂÂÂ for (i = 0; i < len; i++) {
> > +ÂÂÂÂÂÂÂ ret = ctrl->reg_read(ctrl, SWRM_CMD_FIFO_RD_FIFO_ADDR, &val);
> > +ÂÂÂÂÂÂÂ if (ret)
> > +ÂÂÂÂÂÂÂÂÂÂÂ return ret;
> > +
> > +ÂÂÂÂÂÂÂ rval[i] = val & 0xFF;
> > +ÂÂÂ }
> > +
> > +err:
> > +ÂÂÂ spin_lock_irqsave(&ctrl->comp_lock, flags);
> > +ÂÂÂ ctrl->comp = NULL;
> > +ÂÂÂ spin_unlock_irqrestore(&ctrl->comp_lock, flags);
> > +
> > +ÂÂÂ return ret;
> > +}
> > +
> > +static void qcom_swrm_get_device_status(struct qcom_swrm_ctrl *ctrl)
> > +{
> > +ÂÂÂ u32 val;
> > +ÂÂÂ int i;
> > +
> > +ÂÂÂ ctrl->reg_read(ctrl, SWRM_MCP_SLV_STATUS, &val);
>
> Sometimes you test the return value of reg_read(), and sometimes you 
> don't? same for read_write()?
>
> For the Intel stuff, we typically don't check the read/writes to 
> controller registers, but anything that goes out on the bus is checked.

I will try to make this more consistent in next version!

...

> > +
> > +static int qcom_swrm_prepare(struct snd_pcm_substream *substream,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct snd_soc_dai *dai)
> > +{
> > +ÂÂÂ struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dai->dev);
> > +
> > +ÂÂÂ if (!ctrl->sruntime[dai->id])
> > +ÂÂÂÂÂÂÂ return -EINVAL;
> > +
> > +ÂÂÂ return sdw_enable_stream(ctrl->sruntime[dai->id]);
>
> So in hw_params you call sdw_prepare_stream() and in _prepare you call 
> sdw_enable_stream()?
>
> Shouldn't this be handled in a .trigger operation as per the 
> documentation "From ASoC DPCM framework, this stream state is linked to
> .trigger() start operation."

If I move sdw_enable/disable_stream() to trigger I get a big click noise 
on my speakers at start and end of every playback. Tried different 
things but nothing helped so far!. Enabling Speaker DACs only after 
SoundWire ports are enabled is working for me!
There is nothing complicated on WSA881x codec side all the DACs are 
enabled/disabled as part of DAPM.

> It's also my understanding that .prepare will be called multiples times, 

I agree, need to add some extra checks in the prepare to deal with this!

> including for underflows and resume if you don't support INFO_RESUME.

> the sdw_disable_stream() is in .hw_free, which is not necessarily called 
> by the core, so you may have a risk of not being able to recover?

Hmm, I thought hw_free is always called to release resources allocated 
in hw_params.

In what cases does the core not call this?

> > +}
> > +

> > +static int qcom_swrm_hw_free(struct snd_pcm_substream *substream,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct snd_soc_dai *dai)
> > +{
> > +ÂÂÂ struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dai->dev);
> > +ÂÂÂ struct sdw_stream_runtime *sruntime = ctrl->sruntime[dai->id];
> > +
> > +ÂÂÂ qcom_swrm_stream_free_ports(ctrl, sruntime);
> > +ÂÂÂ sdw_stream_remove_master(&ctrl->bus, sruntime);
> > +ÂÂÂ sdw_disable_stream(sruntime);
> > +ÂÂÂ sdw_deprepare_stream(sruntime);
>
> is the order correct here?
>
> On the Intel side we do
>
> trigger_stop:
> sdw_disable_stream(sruntime);
>
> hw_free
> sdw_deprepare_stream(sruntime);
> sdw_stream_remove_master(&ctrl->bus, sruntime);
> sdw_release_stream(dma->stream);

I thought I fixed this one! will be more careful next time!

> > +
> > +ÂÂÂ return 0;
> > +}
> > +
> > +static int qcom_swrm_set_sdw_stream(struct snd_soc_dai *dai,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ void *stream, int direction)
> > +{
> > +ÂÂÂ struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dai->dev);
> > +
> > +ÂÂÂ ctrl->sruntime[dai->id] = stream;
> > +
> > +ÂÂÂ return 0;
> > +}
> > +
> > +static int qcom_swrm_startup(struct snd_pcm_substream *substream,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct snd_soc_dai *dai)
> > +{
> > +ÂÂÂ struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dai->dev);
> > +ÂÂÂ struct snd_soc_pcm_runtime *rtd = substream->private_data;
> > +ÂÂÂ struct sdw_stream_runtime *sruntime;
> > +ÂÂÂ int ret, i;
>
> if you supported pm_runtime, that's where you'd want to take a reference?

I have not tested runtime pm Yet on my setup!

> > +ÂÂÂ sruntime = sdw_alloc_stream(dai->name);
> > +ÂÂÂ if (!sruntime)
> > +ÂÂÂÂÂÂÂ return -ENOMEM;
> > +
> > +ÂÂÂ ctrl->sruntime[dai->id] = sruntime;
> > +
> > +ÂÂÂ for (i = 0; i < rtd->num_codecs; i++) {
> > +ÂÂÂÂÂÂÂ ret = snd_soc_dai_set_sdw_stream(rtd->codec_dais[i], sruntime,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ substream->stream);
> > +ÂÂÂÂÂÂÂ if (ret < 0 && ret != -ENOTSUPP) {
> > +ÂÂÂÂÂÂÂÂÂÂÂ dev_err(dai->dev, "Failed to set sdw stream on %s",
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ rtd->codec_dais[i]->name);
> > +ÂÂÂÂÂÂÂÂÂÂÂ sdw_release_stream(sruntime);
> > +ÂÂÂÂÂÂÂÂÂÂÂ return ret;
> > +ÂÂÂÂÂÂÂ }
> > +ÂÂÂ }
> > +
> > +ÂÂÂ return 0;
> > +}
> > +
> > +static void qcom_swrm_shutdown(struct snd_pcm_substream *substream,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct snd_soc_dai *dai)
> > +{
> > +ÂÂÂ struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dai->dev);
>
> and that's where you'd want to call pm_runtime_put()
>
> > +ÂÂÂ sdw_release_stream(ctrl->sruntime[dai->id]);
> > +ÂÂÂ ctrl->sruntime[dai->id] = NULL;
> > +}
> > +
> > +static const struct snd_soc_dai_ops qcom_swrm_pdm_dai_ops = {
> > +ÂÂÂ .hw_params = qcom_swrm_hw_params,
> > +ÂÂÂ .prepare = qcom_swrm_prepare,
> > +ÂÂÂ .hw_free = qcom_swrm_hw_free,
> > +ÂÂÂ .startup = qcom_swrm_startup,
> > +ÂÂÂ .shutdown = qcom_swrm_shutdown,
> > +ÂÂÂ .set_sdw_stream = qcom_swrm_set_sdw_stream,
>
> no .trigger?
>
> > +};
> > +
> > +static const struct snd_soc_component_driver qcom_swrm_dai_component = {
> > +ÂÂÂ .name = "soundwire",
> > +};
> > +
> > +static int qcom_swrm_register_dais(struct qcom_swrm_ctrl *ctrl)
> > +{
> > +ÂÂÂ int num_dais = ctrl->num_dout_ports + ctrl->num_din_ports;
> > +ÂÂÂ struct snd_soc_dai_driver *dais;
> > +ÂÂÂ struct snd_soc_pcm_stream *stream;
> > +ÂÂÂ struct device *dev = ctrl->dev;
> > +ÂÂÂ int i;
> > +
> > +ÂÂÂ /* PDM dais are only tested for now */
> > +ÂÂÂ dais = devm_kcalloc(dev, num_dais, sizeof(*dais), GFP_KERNEL);
> > +ÂÂÂ if (!dais)
> > +ÂÂÂÂÂÂÂ return -ENOMEM;
> > +
> > +ÂÂÂ for (i = 0; i < num_dais; i++) {
> > +ÂÂÂÂÂÂÂ dais[i].name = devm_kasprintf(dev, GFP_KERNEL, "SDW Pin%d", i);
> > +ÂÂÂÂÂÂÂ if (!dais[i].name)
> > +ÂÂÂÂÂÂÂÂÂÂÂ return -ENOMEM;
>
> I think I mentioned we don't do this in the Intel stuff since it 
> conflicts with topology? is this required on the QCOM side?
yes, we need this for dailink parsing code in machine driver which 
lookup the name from device tree node. If we do not add name at this 
point machine driver will fail to probe as missing dai dependencies.

> > +
> > +ÂÂÂÂÂÂÂ if (i < ctrl->num_dout_ports)
> > +ÂÂÂÂÂÂÂÂÂÂÂ stream = &dais[i].playback;
> > +ÂÂÂÂÂÂÂ else
> > +ÂÂÂÂÂÂÂÂÂÂÂ stream = &dais[i].capture;
> > +
> > +ÂÂÂÂÂÂÂ stream->channels_min = 1;
> > +ÂÂÂÂÂÂÂ stream->channels_max = 1;
> > +ÂÂÂÂÂÂÂ stream->rates = SNDRV_PCM_RATE_48000;
> > +ÂÂÂÂÂÂÂ stream->formats = SNDRV_PCM_FMTBIT_S16_LE;
> > +
> > +ÂÂÂÂÂÂÂ dais[i].ops = &qcom_swrm_pdm_dai_ops;
> > +ÂÂÂÂÂÂÂ dais[i].id = i;
> > +ÂÂÂ }
> > +
> > +ÂÂÂ return devm_snd_soc_register_component(ctrl->dev,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ &qcom_swrm_dai_component,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ dais, num_dais);
> > +}
> > +

...

> > +static int qcom_swrm_runtime_suspend(struct device *device)
> > +{
> > +ÂÂÂ /* TBD */
> > +ÂÂÂ return 0;
> > +}
> > +
> > +static int qcom_swrm_runtime_resume(struct device *device)
> > +{
> > +ÂÂÂ /* TBD */
> > +ÂÂÂ return 0;
> > +}
> > +
> > +static const struct dev_pm_ops qcom_swrm_dev_pm_ops = {
> > +ÂÂÂ SET_RUNTIME_PM_OPS(qcom_swrm_runtime_suspend,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ qcom_swrm_runtime_resume,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ NULL
> > +ÂÂÂ )
> > +};
>
> Maybe define pm_runtime at a later time then? We've had a lot of race 
> conditions to deal with, and it's odd that you don't support plain 
> vanilla suspend first?
Trying to keep things simple for the first patchset! added this dummies 
to keep the soundwire core happy!

thanks,
srini
> > +static const struct of_device_id qcom_swrm_of_match[] = {
> > +ÂÂÂ { .compatible = "qcom,soundwire-v1.3.0", },
> > +ÂÂÂ {/* sentinel */},
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, qcom_swrm_of_match);
> > +
> > +static struct platform_driver qcom_swrm_driver = {
> > +ÂÂÂ .probeÂÂÂ = &qcom_swrm_probe,
> > +ÂÂÂ .remove = &qcom_swrm_remove,
> > +ÂÂÂ .driver = {
> > +ÂÂÂÂÂÂÂ .nameÂÂÂ = "qcom-soundwire",
> > +ÂÂÂÂÂÂÂ .of_match_table = qcom_swrm_of_match,
> > +ÂÂÂÂÂÂÂ .pm = &qcom_swrm_dev_pm_ops,
> > +ÂÂÂ }
> > +};
> > +module_platform_driver(qcom_swrm_driver);
> > +
> > +MODULE_DESCRIPTION("Qualcomm soundwire driver");
> > +MODULE_LICENSE("GPL v2");