[alsa-devel] [PATCH 3/3] soundwire: ignore uniqueID when irrelevant

[Pierre-Louis Bossart]

The uniqueID is useful when there are two or more devices of the same
type (identical manufacturer ID, part ID) on the same link.

When there is a single device of a given type on a link, its uniqueID
is irrelevant. It's not uncommon on actual platforms to see variations
of the uniqueID, or differences between devID registers and ACPI _ADR
fields.

This patch suggests a filter on startup to identify 'single' devices
and tag them accordingly. The uniqueID is then not used for the probe,
and the device name omits the uniqueID as well.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 drivers/soundwire/bus.c   |  7 +++---
 drivers/soundwire/slave.c | 52 ++++++++++++++++++++++++++++++++++++---
 2 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index fc53dbe57f85..be5d437058ed 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -422,10 +422,11 @@ static struct sdw_slave *sdw_get_slave(struct sdw_bus *bus, int i)
 
 static int sdw_compare_devid(struct sdw_slave *slave, struct sdw_slave_id id)
 {
-	if (slave->id.unique_id != id.unique_id ||
-	    slave->id.mfg_id != id.mfg_id ||
+	if (slave->id.mfg_id != id.mfg_id ||
 	    slave->id.part_id != id.part_id ||
-	    slave->id.class_id != id.class_id)
+	    slave->id.class_id != id.class_id ||
+	    (slave->id.unique_id != SDW_IGNORED_UNIQUE_ID &&
+	     slave->id.unique_id != id.unique_id))
 		return -ENODEV;
 
 	return 0;
diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c
index 5dbc76772d21..19919975bb6d 100644
--- a/drivers/soundwire/slave.c
+++ b/drivers/soundwire/slave.c
@@ -29,10 +29,17 @@ static int sdw_slave_add(struct sdw_bus *bus,
 	slave->dev.parent = bus->dev;
 	slave->dev.fwnode = fwnode;
 
-	/* name shall be sdw:link:mfg:part:class:unique */
-	dev_set_name(&slave->dev, "sdw:%x:%x:%x:%x:%x",
-		     bus->link_id, id->mfg_id, id->part_id,
-		     id->class_id, id->unique_id);
+	if (id->unique_id == SDW_IGNORED_UNIQUE_ID) {
+		/* name shall be sdw:link:mfg:part:class */
+		dev_set_name(&slave->dev, "sdw:%x:%x:%x:%x",
+			     bus->link_id, id->mfg_id, id->part_id,
+			     id->class_id);
+	} else {
+		/* name shall be sdw:link:mfg:part:class:unique */
+		dev_set_name(&slave->dev, "sdw:%x:%x:%x:%x:%x",
+			     bus->link_id, id->mfg_id, id->part_id,
+			     id->class_id, id->unique_id);
+	}
 
 	slave->dev.release = sdw_slave_release;
 	slave->dev.bus = &sdw_bus_type;
@@ -103,6 +110,7 @@ static bool find_slave(struct sdw_bus *bus,
 int sdw_acpi_find_slaves(struct sdw_bus *bus)
 {
 	struct acpi_device *adev, *parent;
+	struct acpi_device *adev2, *parent2;
 
 	parent = ACPI_COMPANION(bus->dev);
 	if (!parent) {
@@ -112,10 +120,46 @@ int sdw_acpi_find_slaves(struct sdw_bus *bus)
 
 	list_for_each_entry(adev, &parent->children, node) {
 		struct sdw_slave_id id;
+		struct sdw_slave_id id2;
+		bool ignore_unique_id = true;
 
 		if (!find_slave(bus, adev, &id))
 			continue;
 
+		/* brute-force O(N^2) search for duplicates */
+		parent2 = parent;
+		list_for_each_entry(adev2, &parent2->children, node) {
+
+			if (adev == adev2)
+				continue;
+
+			if (!find_slave(bus, adev2, &id2))
+				continue;
+
+			if (id.sdw_version != id2.sdw_version ||
+			    id.mfg_id != id2.mfg_id ||
+			    id.part_id != id2.part_id ||
+			    id.class_id != id2.class_id)
+				continue;
+
+			if (id.unique_id != id2.unique_id) {
+				dev_dbg(bus->dev,
+					"Valid unique IDs %x %x for Slave mfg %x part %d\n",
+					id.unique_id, id2.unique_id,
+					id.mfg_id, id.part_id);
+				ignore_unique_id = false;
+			} else {
+				dev_err(bus->dev,
+					"Invalid unique IDs %x %x for Slave mfg %x part %d\n",
+					id.unique_id, id2.unique_id,
+					id.mfg_id, id.part_id);
+				return -ENODEV;
+			}
+		}
+
+		if (ignore_unique_id)
+			id.unique_id = SDW_IGNORED_UNIQUE_ID;
+
 		/*
 		 * don't error check for sdw_slave_add as we want to continue
 		 * adding Slaves
-- 
2.20.1