Re: [PATCH 3/3] soundwire: qcom: add clock stop via runtime pm support

[Pierre-Louis Bossart]

> +	pm_runtime_get_sync(ctrl->dev);

if this fails you've got to do a put_noidle().

we use this for Intel:

	ret = pm_runtime_get_sync(cdns->dev);
	if (ret < 0 && ret != -EACCES) {
		dev_err_ratelimited(cdns->dev,
				    "pm_runtime_get_sync failed in %s, ret %d\n",
				    __func__, ret);
		pm_runtime_put_noidle(cdns->dev);
		return ret;
	}


> +	pm_runtime_mark_last_busy(ctrl->dev);
> +	pm_runtime_put_autosuspend(ctrl->dev);
>   
>   	complete(&ctrl->enumeration);
>   	return 0;
> @@ -421,6 +427,7 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
>   	u8 devnum = 0;
>   	int ret = IRQ_HANDLED;
>   
> +	clk_prepare_enable(swrm->hclk);
>   	swrm->reg_read(swrm, SWRM_INTERRUPT_STATUS, &intr_sts);
>   	intr_sts_masked = intr_sts & swrm->intr_mask;
>   
> @@ -529,6 +536,7 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
>   		intr_sts_masked = intr_sts & swrm->intr_mask;
>   	} while (intr_sts_masked);
>   
> +	clk_disable_unprepare(swrm->hclk);
>   	return ret;
>   }
>   
> @@ -587,6 +595,8 @@ static enum sdw_command_response qcom_swrm_xfer_msg(struct sdw_bus *bus,
>   	struct qcom_swrm_ctrl *ctrl = to_qcom_sdw(bus);
>   	int ret, i, len;
>   
> +	pm_runtime_get_sync(ctrl->dev);
> +
>   	if (msg->flags == SDW_MSG_FLAG_READ) {
>   		for (i = 0; i < msg->len;) {
>   			if ((msg->len - i) < QCOM_SWRM_MAX_RD_LEN)
> @@ -598,7 +608,7 @@ static enum sdw_command_response qcom_swrm_xfer_msg(struct sdw_bus *bus,
>   							msg->addr + i, len,
>   						       &msg->buf[i]);
>   			if (ret)
> -				return ret;
> +				goto done;
>   
>   			i = i + len;
>   		}
> @@ -607,12 +617,20 @@ static enum sdw_command_response qcom_swrm_xfer_msg(struct sdw_bus *bus,
>   			ret = qcom_swrm_cmd_fifo_wr_cmd(ctrl, msg->buf[i],
>   							msg->dev_num,
>   						       msg->addr + i);
> -			if (ret)
> -				return SDW_CMD_IGNORED;
> +			if (ret) {
> +				ret = SDW_CMD_IGNORED;
> +				goto done;
> +			}
>   		}
>   	}
>   
> +	pm_runtime_put_autosuspend(ctrl->dev);
> +	pm_runtime_mark_last_busy(ctrl->dev);

wrong order, you've got to mark_last_busy before the put().

>   	return SDW_CMD_OK;
> +done:
> +	pm_runtime_mark_last_busy(ctrl->dev);
> +	pm_runtime_put_autosuspend(ctrl->dev);
> +	return ret;

this looks weird. why not reuse the same flow and return ret in all cases?

>   }
>   
>   static int qcom_swrm_pre_bank_switch(struct sdw_bus *bus)
> @@ -620,13 +638,19 @@ static int qcom_swrm_pre_bank_switch(struct sdw_bus *bus)
>   	u32 reg = SWRM_MCP_FRAME_CTRL_BANK_ADDR(bus->params.next_bank);
>   	struct qcom_swrm_ctrl *ctrl = to_qcom_sdw(bus);
>   	u32 val;
> +	int ret;
>   
> +	pm_runtime_get_sync(ctrl->dev);
>   	ctrl->reg_read(ctrl, reg, &val);
>   
>   	u32p_replace_bits(&val, ctrl->cols_index, SWRM_MCP_FRAME_CTRL_BANK_COL_CTRL_BMSK);
>   	u32p_replace_bits(&val, ctrl->rows_index, SWRM_MCP_FRAME_CTRL_BANK_ROW_CTRL_BMSK);
>   
> -	return ctrl->reg_write(ctrl, reg, val);
> +	ret = ctrl->reg_write(ctrl, reg, val);
> +	pm_runtime_mark_last_busy(ctrl->dev);
> +	pm_runtime_put_autosuspend(ctrl->dev);
> +
> +	return ret;
>   }
>   
>   static int qcom_swrm_port_params(struct sdw_bus *bus,
> @@ -634,13 +658,18 @@ static int qcom_swrm_port_params(struct sdw_bus *bus,
>   				 unsigned int bank)
>   {
>   	struct qcom_swrm_ctrl *ctrl = to_qcom_sdw(bus);
> +	int ret = 0;
> +	pm_runtime_get_sync(ctrl->dev);
>   
>   	if (p_params->bps != SWR_INVALID_PARAM)
> -		return ctrl->reg_write(ctrl,
> +		ret = ctrl->reg_write(ctrl,
>   				       SWRM_DP_BLOCK_CTRL_1(p_params->num),
>   				       p_params->bps - 1);
> +	pm_runtime_mark_last_busy(ctrl->dev);
> +	pm_runtime_put_autosuspend(ctrl->dev);

it feels like all you pm_runtime_get/put() should be moved to your 
register read/write operations?

>   
> -	return 0;
> +
> +	return ret;
>   }
>   
>   static int qcom_swrm_transport_params(struct sdw_bus *bus,
> @@ -651,6 +680,7 @@ static int qcom_swrm_transport_params(struct sdw_bus *bus,
>   	u32 value;
>   	int reg = SWRM_DP_PORT_CTRL_BANK((params->port_num), bank);
>   	int ret;
> +	pm_runtime_get_sync(ctrl->dev);
>   
>   	value = params->offset1 << SWRM_DP_PORT_CTRL_OFFSET1_SHFT;
>   	value |= params->offset2 << SWRM_DP_PORT_CTRL_OFFSET2_SHFT;
> @@ -685,6 +715,9 @@ static int qcom_swrm_transport_params(struct sdw_bus *bus,
>   		reg = SWRM_DP_BLOCK_CTRL3_BANK(params->port_num, bank);
>   		ret = ctrl->reg_write(ctrl, reg, params->blk_pkg_mode);
>   	}
> +	pm_runtime_mark_last_busy(ctrl->dev);
> +	pm_runtime_put_autosuspend(ctrl->dev);
> +
>   
>   	return ret;
>   }
> @@ -696,6 +729,9 @@ static int qcom_swrm_port_enable(struct sdw_bus *bus,
>   	u32 reg = SWRM_DP_PORT_CTRL_BANK(enable_ch->port_num, bank);
>   	struct qcom_swrm_ctrl *ctrl = to_qcom_sdw(bus);
>   	u32 val;
> +	int ret;
> +
> +	pm_runtime_get_sync(ctrl->dev);
>   
>   	ctrl->reg_read(ctrl, reg, &val);
>   
> @@ -704,7 +740,11 @@ static int qcom_swrm_port_enable(struct sdw_bus *bus,
>   	else
>   		val &= ~(0xff << SWRM_DP_PORT_CTRL_EN_CHAN_SHFT);
>   
> -	return ctrl->reg_write(ctrl, reg, val);
> +	ret  = ctrl->reg_write(ctrl, reg, val);
> +	pm_runtime_mark_last_busy(ctrl->dev);
> +	pm_runtime_put_autosuspend(ctrl->dev);
> +
> +	return ret;
>   }
>   
>   static const struct sdw_master_port_ops qcom_swrm_port_ops = {
> @@ -1194,6 +1234,13 @@ static int qcom_swrm_probe(struct platform_device *pdev)
>   		 (ctrl->version >> 24) & 0xff, (ctrl->version >> 16) & 0xff,
>   		 ctrl->version & 0xffff);
>   
> +	pm_runtime_set_autosuspend_delay(dev, 30000);

30s? that sounds very very long for an audio device.

> +	pm_runtime_use_autosuspend(dev);
> +	pm_runtime_mark_last_busy(dev);
> +
> +	pm_runtime_set_active(dev);
> +	pm_runtime_enable(dev);
> +
>   	return 0;
>   
>   err_master_add:
> @@ -1214,6 +1261,47 @@ static int qcom_swrm_remove(struct platform_device *pdev)
>   	return 0;
>   }
>   
> +static int swrm_runtime_resume(struct device *dev)
> +{
> +	struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dev);
> +
> +	reinit_completion(&ctrl->enumeration);
> +	clk_prepare_enable(ctrl->hclk);
> +	ctrl->reg_write(ctrl, SWRM_COMP_SW_RESET, 0x01);
> +	qcom_swrm_get_device_status(ctrl);
> +	sdw_handle_slave_status(&ctrl->bus, ctrl->status);
> +	qcom_swrm_init(ctrl);
> +	wait_for_completion_timeout(&ctrl->enumeration,
> +					msecs_to_jiffies(TIMEOUT_MS));
> +	usleep_range(100, 105);
> +
> +	pm_runtime_mark_last_busy(dev);

Humm, what 'clock stop' are we talking about here?

In SoundWire 1.x devices, you can stop the BUS clock and not have to 
redo any enumeration on resume, devices are required to save their 
context.  You have to also follow the pattern of preparing and 
broadcasting the CLOCK STOP NOW message.

It looks like you are stopping something else, and completely resetting 
the hardware. It's fine, it's just a reset but not clock stop support as 
defined in the SoundWire spec.

> +
> +	return 0;
> +}
> +
> +static int __maybe_unused swrm_runtime_suspend(struct device *dev)
> +{
> +	struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dev);
> +
> +	/* 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);
> +	/* clock stop sequence */
> +	qcom_swrm_cmd_fifo_wr_cmd(ctrl, 0x2, 0xF, SDW_SCP_CTRL);

Humm, this looks like writing in SCP_CTRL::ClockStopNow, so why is 
enumeration required on restart?

If you take down the bus and reset everything, you don't need to do this 
sequence. a hardware reset will do...

> +
> +	clk_disable_unprepare(ctrl->hclk);
> +
> +	usleep_range(100, 105);
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops swrm_dev_pm_ops = {
> +	SET_RUNTIME_PM_OPS(swrm_runtime_suspend, swrm_runtime_resume, NULL)
> +};
> +
>   static const struct of_device_id qcom_swrm_of_match[] = {
>   	{ .compatible = "qcom,soundwire-v1.3.0", .data = &swrm_v1_3_data },
>   	{ .compatible = "qcom,soundwire-v1.5.1", .data = &swrm_v1_5_data },
> @@ -1228,6 +1316,7 @@ static struct platform_driver qcom_swrm_driver = {
>   	.driver = {
>   		.name	= "qcom-soundwire",
>   		.of_match_table = qcom_swrm_of_match,
> +		.pm = &swrm_dev_pm_ops,
>   	}
>   };
>   module_platform_driver(qcom_swrm_driver);