Re: [PATCH v2 1/3] soundwire: qcom: add runtime pm support

[Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>]

On 24/02/2022 15:41, Pierre-Louis Bossart wrote:
> >   static const struct snd_soc_dai_ops qcom_swrm_pdm_dai_ops = {
> > @@ -1197,12 +1224,23 @@ static int qcom_swrm_get_port_config(struct qcom_swrm_ctrl *ctrl)
> >   static int swrm_reg_show(struct seq_file *s_file, void *data)
> >   {
> >   	struct qcom_swrm_ctrl *swrm = s_file->private;
> > -	int reg, reg_val;
> > +	int reg, reg_val, ret;
> > +
> > +	ret = pm_runtime_get_sync(swrm->dev);
> > +	if (ret < 0 && ret != -EACCES) {
> > +		dev_err_ratelimited(swrm->dev,
> > +				    "pm_runtime_get_sync failed in %s, ret %d\n",
> > +				    __func__, ret);
> > +		pm_runtime_put_noidle(swrm->dev);
> > +	}
> >   
> >   	for (reg = 0; reg <= SWR_MSTR_MAX_REG_ADDR; reg += 4) {
> >   		swrm->reg_read(swrm, reg, &reg_val);
> >   		seq_printf(s_file, "0x%.3x: 0x%.2x\n", reg, reg_val);
> >   	}
> > +	pm_runtime_mark_last_busy(swrm->dev);
> > +	pm_runtime_put_autosuspend(swrm->dev);
> > +
>
> question: is there a reason why this specific set of reg_read() is
> surrounded pm_runtime stuff? Is this saying that in all other case where
> the callback is used, the controller is already resumed and fully
> operational? That's be worthy of a comment.

controller register reads require clk to be ON, which might not be 
always ON. In suspended case we switch off the clocks.

Other places so far that I have seen is that controller is either 
already resumed or clk is on (interrupt case) and resume case.



> > struct qcom_swrm_ctrl *swrm
> > struct qcom_swrm_ctrl *ctrl
>
> nit-pick: it helps reviewers when the same variable name is used
> consistently.

Yes, I did notice this, but for some reason I forgot to fix it.

> > +static int __maybe_unused swrm_runtime_suspend(struct device *dev)
> > +{
> > +	struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dev);
> > +	int ret;
> > +
> > +	if (!ctrl->clock_stop_not_supported) {
> > +		/* Mask bus clash interrupt */
> > +		ctrl->intr_mask &= ~SWRM_INTERRUPT_STATUS_MASTER_CLASH_DET;
> > +		ctrl->reg_write(ctrl, SWRM_INTERRUPT_MASK_ADDR, ctrl->intr_mask);
> > +		ctrl->reg_write(ctrl, SWRM_INTERRUPT_CPU_EN, ctrl->intr_mask);
> > +	}
> > +	/* Prepare slaves for clock stop */
> > +	ret = sdw_bus_prep_clk_stop(&ctrl->bus);
> > +	if (ret < 0) {
>
> if (ret < 0 && ret != -ENODATA) {
>
> ?
>
> > +		dev_err(dev, "prepare clock stop failed %d", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = sdw_bus_clk_stop(&ctrl->bus);
> > +	if (ret < 0 && ret != -ENODATA) {
> > +		dev_err(dev, "bus clock stop failed %d", ret);
> > +		return ret;
> > +	}
> > +
> > +	clk_disable_unprepare(ctrl->hclk);
> > +
> > +	usleep_range(300, 305);
> > +
> > +	return 0;
> > +}