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

Srinivas Kandagatla
2022-02-24T15:59:10Z

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;
>> +}