soundwire: bus: add dev_warn() messages to track UNATTACHED devices

In rare cases, some devices seem to lose sync and never re-attach on
the bus. This seems to happen only when there are more than one device
per link, which suggests either an electrical issue, a race condition
or a state machine issue.

Add two dev_warn() messages to identify the sequence by which the
devices become UNATTACHED.

BugLink: https://github.com/thesofproject/linux/issues/3063
BugLink: https://github.com/thesofproject/linux/issues/3325
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20220126011527.27930-1-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 67369e941d0d69f1bc63e28c31925d4b7b77a4d0..354d3f89366f6f3b7982b4129bdda7015c9c93fe 100644 (file)
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -1749,8 +1749,11 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
                        continue;
 
                if (status[i] == SDW_SLAVE_UNATTACHED &&
-                   slave->status != SDW_SLAVE_UNATTACHED)
+                   slave->status != SDW_SLAVE_UNATTACHED) {
+                       dev_warn(&slave->dev, "Slave %d state check1: UNATTACHED, status was %d\n",
+                                i, slave->status);
                        sdw_modify_slave_status(slave, SDW_SLAVE_UNATTACHED);
+               }
        }
 
        if (status[0] == SDW_SLAVE_ATTACHED) {
@@ -1785,6 +1788,9 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
                        if (slave->status == SDW_SLAVE_UNATTACHED)
                                break;
 
+                       dev_warn(&slave->dev, "Slave %d state check2: UNATTACHED, status was %d\n",
+                                i, slave->status);
+
                        sdw_modify_slave_status(slave, SDW_SLAVE_UNATTACHED);
                        break;