Workqueue-based probe and notification callback

sound/soc/sof/Kconfig

@@ -144,6 +144,14 @@ config SND_SOC_SOF
 	  module dependencies but since the module or built-in type is decided
 	  at the top level it doesn't matter.
 
+config SND_SOC_SOF_PROBE_WORK_QUEUE
+	bool
+	help
+          This option is not user-selectable but automagically handled by
+	  'select' statements at a higher level
+	  When selected, the probe is handled in two steps, for example to
+	  avoid lockdeps if request_module is used in the probe.
+
 source "sound/soc/sof/intel/Kconfig"
 source "sound/soc/sof/xtensa/Kconfig"
 

sound/soc/sof/core.c

@@ -255,47 +255,14 @@ static int sof_machine_check(struct snd_sof_dev *sdev)
 	return 0;
 }
 
-int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
+static int sof_probe_continue(struct snd_sof_dev *sdev)
 {
-	struct snd_sof_dev *sdev;
+	struct snd_sof_pdata *plat_data = sdev->pdata;
 	const char *drv_name;
 	const void *mach;
 	int size;
 	int ret;
 
-	sdev = devm_kzalloc(dev, sizeof(*sdev), GFP_KERNEL);
-	if (!sdev)
-		return -ENOMEM;
-
-	dev_dbg(dev, "probing SOF DSP device....\n");
-
-	/* initialize sof device */
-	sdev->dev = dev;
-	if dev_is_pci(plat_data->dev)
-		sdev->pci = to_pci_dev(plat_data->dev);
-
-	sdev->pdata = plat_data;
-	sdev->first_boot = true;
-	dev_set_drvdata(dev, sdev);
-
-	INIT_LIST_HEAD(&sdev->pcm_list);
-	INIT_LIST_HEAD(&sdev->kcontrol_list);
-	INIT_LIST_HEAD(&sdev->widget_list);
-	INIT_LIST_HEAD(&sdev->dai_list);
-	INIT_LIST_HEAD(&sdev->route_list);
-	spin_lock_init(&sdev->ipc_lock);
-	spin_lock_init(&sdev->hw_lock);
-
-	/* set default timeouts if none provided */
-	if (plat_data->desc->ipc_timeout == 0)
-		sdev->ipc_timeout = TIMEOUT_DEFAULT_IPC_MS;
-	else
-		sdev->ipc_timeout = plat_data->desc->ipc_timeout;
-	if (plat_data->desc->boot_timeout == 0)
-		sdev->boot_timeout = TIMEOUT_DEFAULT_BOOT_MS;
-	else
-		sdev->boot_timeout = plat_data->desc->boot_timeout;
-
 	/* probe the DSP hardware */
 	ret = snd_sof_probe(sdev);
 	if (ret < 0) {
@@ -362,7 +329,7 @@ int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
 	sdev->first_boot = false;
 
 	/* now register audio DSP platform driver and dai */
-	ret = snd_soc_register_component(dev, &sdev->plat_drv,
+	ret = snd_soc_register_component(sdev->dev, &sdev->plat_drv,
 					 sof_ops(sdev)->drv,
 					 sof_ops(sdev)->num_drv);
 	if (ret < 0) {
@@ -388,10 +355,13 @@ int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
 	dev_dbg(sdev->dev, "created machine %s\n",
 		dev_name(&plat_data->pdev_mach->dev));
 
+	if (plat_data->sof_probe_complete)
+		plat_data->sof_probe_complete(sdev->dev);
+
 	return 0;
 
 comp_err:
-	snd_soc_unregister_component(dev);
+	snd_soc_unregister_component(sdev->dev);
 fw_run_err:
 	snd_sof_fw_unload(sdev);
 fw_load_err:
@@ -403,13 +373,81 @@ int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
 
 	return ret;
 }
+
+#if IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE)
+static void sof_probe_work(struct work_struct *work)
+{
+	struct snd_sof_dev *sdev =
+		container_of(work, struct snd_sof_dev, probe_work);
+	int ret;
+
+	dev_dbg(sdev->dev, "%s entry\n", __func__);
+	ret = sof_probe_continue(sdev);
+	if (ret < 0) {
+		/* errors cannot be propagated, log */
+		dev_err(sdev->dev, "error: %s failed err: %d\n", __func__, ret);
+	}
+}
+#endif
+
+int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
+{
+	struct snd_sof_dev *sdev;
+
+	sdev = devm_kzalloc(dev, sizeof(*sdev), GFP_KERNEL);
+	if (!sdev)
+		return -ENOMEM;
+
+	dev_dbg(dev, "probing SOF DSP device....\n");
+
+	/* initialize sof device */
+	sdev->dev = dev;
+	if dev_is_pci(plat_data->dev)
+		sdev->pci = to_pci_dev(plat_data->dev);
+
+	sdev->pdata = plat_data;
+	sdev->first_boot = true;
+	dev_set_drvdata(dev, sdev);
+
+	INIT_LIST_HEAD(&sdev->pcm_list);
+	INIT_LIST_HEAD(&sdev->kcontrol_list);
+	INIT_LIST_HEAD(&sdev->widget_list);
+	INIT_LIST_HEAD(&sdev->dai_list);
+	INIT_LIST_HEAD(&sdev->route_list);
+	spin_lock_init(&sdev->ipc_lock);
+	spin_lock_init(&sdev->hw_lock);
+
+#if IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE)
+	INIT_WORK(&sdev->probe_work, sof_probe_work);
+#endif
+
+	/* set default timeouts if none provided */
+	if (plat_data->desc->ipc_timeout == 0)
+		sdev->ipc_timeout = TIMEOUT_DEFAULT_IPC_MS;
+	else
+		sdev->ipc_timeout = plat_data->desc->ipc_timeout;
+	if (plat_data->desc->boot_timeout == 0)
+		sdev->boot_timeout = TIMEOUT_DEFAULT_BOOT_MS;
+	else
+		sdev->boot_timeout = plat_data->desc->boot_timeout;
+
+	if (IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE)) {
+		schedule_work(&sdev->probe_work);
+		return 0;
+	}
+
+	return sof_probe_continue(sdev);
+}
 EXPORT_SYMBOL(snd_sof_device_probe);
 
 int snd_sof_device_remove(struct device *dev)
 {
 	struct snd_sof_dev *sdev = dev_get_drvdata(dev);
 	struct snd_sof_pdata *pdata = sdev->pdata;
 
+	if (IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE))
+		cancel_work_sync(&sdev->probe_work);
+
 	snd_soc_unregister_component(dev);
 	snd_sof_fw_unload(sdev);
 	snd_sof_ipc_free(sdev);

sound/soc/sof/intel/Kconfig

@@ -215,6 +215,7 @@ if SND_SOC_SOF_HDA_COMMON
 
 config SND_SOC_SOF_HDA_LINK
 	bool "SOF support for HDA Links(HDA/HDMI)"
+	select SND_SOC_SOF_PROBE_WORK_QUEUE
 	help
           This adds support for HDA links(HDA/HDMI) with Sound Open Firmware
 		  for Intel(R) platforms.

sound/soc/sof/sof-pci-dev.c

@@ -150,6 +150,24 @@ static const struct dev_pm_ops sof_pci_pm = {
 			   NULL)
 };
 
+static void sof_pci_probe_complete(struct device *dev)
+{
+	dev_dbg(dev, "Completing SOF PCI probe");
+
+	/* allow runtime_pm */
+	pm_runtime_set_autosuspend_delay(dev, SND_SOF_SUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(dev);
+
+	/*
+	 * runtime pm for pci device is "forbidden" by default.
+	 * so call pm_runtime_allow() to enable it.
+	 */
+	pm_runtime_allow(dev);
+
+	/* follow recommendation in pci-driver.c to decrement usage counter */
+	pm_runtime_put_noidle(dev);
+}
+
 static int sof_pci_probe(struct pci_dev *pci,
 			 const struct pci_device_id *pci_id)
 {
@@ -209,25 +227,20 @@ static int sof_pci_probe(struct pci_dev *pci,
 	sof_pdata->dev = dev;
 	sof_pdata->platform = dev_name(dev);
 
+#if IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE)
+	/* set callback to enable runtime_pm */
+	sof_pdata->sof_probe_complete = sof_pci_probe_complete;
+#endif
 	/* call sof helper for DSP hardware probe */
 	ret = snd_sof_device_probe(dev, sof_pdata);
 	if (ret) {
 		dev_err(dev, "error: failed to probe DSP hardware!\n");
 		goto release_regions;
 	}
 
-	/* allow runtime_pm */
-	pm_runtime_set_autosuspend_delay(dev, SND_SOF_SUSPEND_DELAY_MS);
-	pm_runtime_use_autosuspend(dev);
-
-	/*
-	 * runtime pm for pci device is "forbidden" by default.
-	 * so call pm_runtime_allow() to enable it.
-	 */
-	pm_runtime_allow(dev);
-
-	/* follow recommendation in pci-driver.c to decrement usage counter */
-	pm_runtime_put_noidle(dev);
+#if !IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE)
+	sof_pci_probe_complete(dev);
+#endif
 
 	return ret;
 

sound/soc/sof/sof-priv.h

@@ -314,6 +314,9 @@ struct snd_sof_dev {
 	u32 boot_complete;
 	u32 first_boot;
 
+	/* work queue in case the probe is implemented in two steps */
+	struct work_struct probe_work;
+
 	/* DSP HW differentiation */
 	struct snd_sof_pdata *pdata;