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

On 22/02/2022 19:15, Pierre-Louis Bossart wrote:

On 2/21/22 04:41, Srinivas Kandagatla wrote:

...

Add support to runtime PM using SoundWire clock stop on supported instances and bus reset on instances that require full reset.

This commit message and code are a bit confusing, e.g. you have a boolean state

ctrl->clk_stop_bus_reset = true;

Does this mean bus reset on exiting clock stop? or just that clock stop is not supported and bus reset is required with complete re-enumeration.

WSA instances of SoundWire controllers do not support clk stop and a reset of ip is required with complete re-enumeration when a clock is cut off during suspend.

It would be good to try and explain using SoundWire 1.x terminology what actions are taken on resume.

There are two cases here.

1> Controller Instance support ClockStop Mode0, we mostly use the generic core to do that except in resume path we make sure that we start the clock.

2> Controller Instances which that do not support ClockStop, we do soft reset of controller along with hard resetting slaves.

...

@@ -1267,6 +1305,7 @@ static int qcom_swrm_probe(struct platform_device *pdev) ctrl->bus.ops = &qcom_swrm_ops; ctrl->bus.port_ops = &qcom_swrm_port_ops; ctrl->bus.compute_params = &qcom_swrm_compute_params;

• ctrl->bus.clk_stop_timeout = 300;

  ret = qcom_swrm_get_port_config(ctrl); if (ret)

@@ -1319,6 +1358,21 @@ 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, 3000);
• pm_runtime_use_autosuspend(dev);
• pm_runtime_mark_last_busy(dev);
• pm_runtime_set_active(dev);
• pm_runtime_enable(dev);
• /* Clk stop is not supported on WSA Soundwire masters */
• if (ctrl->version <= 0x01030000) {

• ctrl->clk_stop_bus_reset = true;
  

• } else {

• ctrl->reg_read(ctrl, SWRM_COMP_MASTER_ID, &val);
  

• if (val == MASTER_ID_WSA)
  

• 	ctrl->clk_stop_bus_reset = true;
  

• }

I think this means clock_stop_not_supported?

Yes It makes more sense to reword this to clock_stop_not_supported.

...

+static int swrm_runtime_resume(struct device *dev) +{

• struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dev);
• int ret;
• clk_prepare_enable(ctrl->hclk);
• if (ctrl->clk_stop_bus_reset) {

• reinit_completion(&ctrl->enumeration);
  

• ctrl->reg_write(ctrl, SWRM_COMP_SW_RESET, 0x01);
  

• qcom_swrm_get_device_status(ctrl);
  

don't you need some sort of delay before checking the controller and device status? The bus reset sequence takes 4096 bits, that's a non-zero time.

This is soft reset not full Bus Reset as WSA slaves have hard reset pins that will be toggled as part of suspend-resume.

...

• sdw_handle_slave_status(&ctrl->bus, ctrl->status);
  

• qcom_swrm_init(ctrl);
  

• wait_for_completion_timeout(&ctrl->enumeration,
  

• 			    msecs_to_jiffies(TIMEOUT_MS));
  

• } else {

• ctrl->reg_write(ctrl, SWRM_MCP_BUS_CTRL, SWRM_MCP_BUS_CLK_START);
  

• ctrl->reg_write(ctrl, SWRM_INTERRUPT_CLEAR,
  

• 	SWRM_INTERRUPT_STATUS_MASTER_CLASH_DET);
  

• 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);
  

• usleep_range(100, 105);
  

• }
• if (!swrm_wait_for_frame_gen_enabled(ctrl))

• dev_err(ctrl->dev, "link failed to connect\n");
  

• usleep_range(300, 305);
• ret = sdw_bus_exit_clk_stop(&ctrl->bus);
• if (ret < 0)

• dev_err(ctrl->dev, "bus failed to exit clock stop %d\n", ret);
  

• return 0;

+}

+static int __maybe_unused swrm_runtime_suspend(struct device *dev) +{

• struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dev);
• int ret;
• if (!ctrl->clk_stop_bus_reset) {

• /* 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 a device has lost sync and reports -ENODATA, you want still want to go ahead and not prevent the suspend operation from happening.

okay.

--srini

...

• 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;

+}

+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 },

@@ -1359,6 +1506,7 @@ 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);