ASoC/SoundWire: remove ghost peripherals from the mach table

drivers/soundwire/bus.c

@@ -161,7 +161,13 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
 	bus->params.curr_dr_freq = bus->params.max_dr_freq;
 	bus->params.curr_bank = SDW_BANK0;
 	bus->params.next_bank = SDW_BANK1;
+	/*
+	 * Set is_present = true by default. It will be set to false when no peripherals
+	 * are attached on the bus.
+	 */
+	bus->is_present = true;
 
+	init_completion(&bus->enumeration_complete);
 	return 0;
 }
 EXPORT_SYMBOL(sdw_bus_master_add);
@@ -308,13 +314,16 @@ int sdw_transfer(struct sdw_bus *bus, struct sdw_msg *msg)
  * sdw_show_ping_status() - Direct report of PING status, to be used by Peripheral drivers
  * @bus: SDW bus
  * @sync_delay: Delay before reading status
+ *
+ * returns 0 if there is no peripherals attached, 1 if there are peripherals attached
+ * or a negative error code.
  */
-void sdw_show_ping_status(struct sdw_bus *bus, bool sync_delay)
+int sdw_show_ping_status(struct sdw_bus *bus, bool sync_delay)
 {
 	u32 status;
 
 	if (!bus->ops->read_ping_status)
-		return;
+		return -ENOTSUPP;
 
 	/*
 	 * wait for peripheral to sync if desired. 10-15ms should be more than
@@ -329,10 +338,13 @@ void sdw_show_ping_status(struct sdw_bus *bus, bool sync_delay)
 
 	mutex_unlock(&bus->msg_lock);
 
-	if (!status)
+	if (!status) {
 		dev_warn(bus->dev, "%s: no peripherals attached\n", __func__);
-	else
-		dev_dbg(bus->dev, "PING status: %#x\n", status);
+		return 0;
+	}
+
+	dev_dbg(bus->dev, "PING status: %#x\n", status);
+	return 1;
 }
 EXPORT_SYMBOL(sdw_show_ping_status);
 
@@ -847,6 +859,7 @@ static int sdw_program_device_num(struct sdw_bus *bus, bool *programmed)
 		if (ret == -ENODATA) { /* end of device id reads */
 			dev_dbg(bus->dev, "No more devices to enumerate\n");
 			ret = 0;
+			complete_all(&bus->enumeration_complete);
 			break;
 		}
 		if (ret < 0) {

include/linux/soundwire/sdw.h

@@ -901,7 +901,7 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
 		       struct fwnode_handle *fwnode);
 void sdw_bus_master_delete(struct sdw_bus *bus);
 
-void sdw_show_ping_status(struct sdw_bus *bus, bool sync_delay);
+int sdw_show_ping_status(struct sdw_bus *bus, bool sync_delay);
 
 /**
  * struct sdw_port_config: Master or Slave Port configuration
@@ -1001,6 +1001,8 @@ struct sdw_stream_runtime {
  * transport and port parameters
  * @defer_msg: Defer message
  * @params: Current bus parameters
+ * @enumeration_complete: completion utility to control potential races between
+ * enumeration completion and peripheral presence checks.
  * @stream_refcount: number of streams currently using this bus
  * @bpt_stream_refcount: number of BTP streams currently using this bus (should
  * be zero or one, multiple streams per link is not supported).
@@ -1029,6 +1031,7 @@ struct sdw_stream_runtime {
  * are supported. This flag is populated by drivers after reading
  * appropriate firmware (ACPI/DT).
  * @lane_used_bandwidth: how much bandwidth in bits per second is used by each lane
+ * @is_present: indicates whether any peripheral is present on the bus.
  */
 struct sdw_bus {
 	struct device *dev;
@@ -1042,6 +1045,7 @@ struct sdw_bus {
 	struct list_head m_rt_list;
 	struct sdw_defer defer_msg;
 	struct sdw_bus_params params;
+	struct completion enumeration_complete;
 	int stream_refcount;
 	int bpt_stream_refcount;
 	struct sdw_stream_runtime *bpt_stream;
@@ -1064,6 +1068,7 @@ struct sdw_bus {
 #endif
 	bool multi_link;
 	unsigned int lane_used_bandwidth[SDW_MAX_LANES];
+	bool is_present;
 };
 
 struct sdw_stream_runtime *sdw_alloc_stream(const char *stream_name, enum sdw_stream_type type);

sound/soc/sof/intel/hda.c

@@ -1304,6 +1304,8 @@ static struct snd_soc_acpi_adr_device *find_acpi_adr_device(struct device *dev,
 	return adr_dev;
 }
 
+#define SDW_ENUM_TIMEOUT_MS 3000
+
 static struct snd_soc_acpi_mach *hda_sdw_machine_select(struct snd_sof_dev *sdev)
 {
 	struct snd_sof_pdata *pdata = sdev->pdata;
@@ -1313,7 +1315,9 @@ static struct snd_soc_acpi_mach *hda_sdw_machine_select(struct snd_sof_dev *sdev
 	struct sdw_peripherals *peripherals;
 	struct snd_soc_acpi_mach *mach;
 	struct sof_intel_hda_dev *hdev;
+	struct sdw_slave *slave;
 	int link_index, link_num;
+	unsigned long time;
 	int amp_index = 1;
 	u32 link_mask = 0;
 	int i;
@@ -1415,14 +1419,53 @@ static struct snd_soc_acpi_mach *hda_sdw_machine_select(struct snd_sof_dev *sdev
 	if (!links)
 		return NULL;
 
+	/*
+	 * Recalculate the link_mask as a link will be empty if all peripherals on the link are
+	 * not enumerated
+	 */
+	link_mask = 0;
 	/* Generate snd_soc_acpi_link_adr struct for each peripheral reported by the ACPI table */
 	for (i = 0; i < peripherals->num_peripherals; i++) {
+		slave = peripherals->array[i];
+
+		if (!slave->bus->is_present)
+			continue;
+
+		if (link_mask & BIT(slave->bus->link_id)) {
+			/*
+			 * At least one peripheral is present on the link which means that this
+			 * link has already been enumerated
+			 */
+			goto skip_wait_link_enumeration;
+		}
+
+		if (sdw_show_ping_status(slave->bus, true) == 0) {
+			/* no peripherals attached on this link */
+			slave->bus->is_present = false;
+			continue;
+		}
+
+		time = wait_for_completion_timeout(&slave->bus->enumeration_complete,
+						   msecs_to_jiffies(SDW_ENUM_TIMEOUT_MS));
+		if (!time) {
+			dev_warn(slave->bus->dev, "No peripheral is present\n");
+			slave->bus->is_present = false;
+			continue;
+		}
+
+skip_wait_link_enumeration:
+		/* Check if the SoundWire peripheral is present */
+		if (!slave->dev_num_sticky) {
+			dev_warn(&slave->dev, "SoundWire peripheral is not present\n");
+			continue;
+		}
 		/* link_index = the number of used links below the current link */
-		link_index = hweight32(link_mask & (BIT(peripherals->array[i]->bus->link_id) - 1));
-		links[link_index].adr_d = find_acpi_adr_device(sdev->dev, peripherals->array[i],
+		link_index = hweight32(link_mask & (BIT(slave->bus->link_id) - 1));
+		links[link_index].adr_d = find_acpi_adr_device(sdev->dev, slave,
 							       &links[link_index], &amp_index);
 		if (!links[link_index].adr_d)
 			return NULL;
+		link_mask |= BIT(slave->bus->link_id);
 	}
 
 	mach->drv_name = "sof_sdw";