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soundwire: bus: fix race condition with enumeration_complete signaling

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This patch adds the signaling needed for Slave drivers to wait until
the enumeration completes so that race conditions when issuing
read/write commands are avoided. The calls for wait_for_completion()
will be added in codec drivers in follow-up patches.

The order between init_completion() and complete() is deterministic,
the Slave is marked as UNATTACHED either during a Master-initiated
HardReset, or when the hardware detects the Slave no longer reports as
ATTACHED.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200115000844.14695-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Pierre-Louis Bossart 2020-01-14 18:08:36 -06:00 committed by Vinod Koul
parent 2140b66b5d
commit fb9469e54f
2 changed files with 21 additions and 0 deletions
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20
drivers/soundwire/bus.c
View File

@ -610,6 +610,26 @@ static void sdw_modify_slave_status(struct sdw_slave *slave,
enum sdw_slave_status status)
{
mutex_lock(&slave->bus->bus_lock);
dev_vdbg(&slave->dev,
"%s: changing status slave %d status %d new status %d\n",
__func__, slave->dev_num, slave->status, status);
if (status == SDW_SLAVE_UNATTACHED) {
dev_dbg(&slave->dev,
"%s: initializing completion for Slave %d\n",
__func__, slave->dev_num);
init_completion(&slave->enumeration_complete);
} else if ((status == SDW_SLAVE_ATTACHED) &&
(slave->status == SDW_SLAVE_UNATTACHED)) {
dev_dbg(&slave->dev,
"%s: signaling completion for Slave %d\n",
__func__, slave->dev_num);
complete(&slave->enumeration_complete);
}
slave->status = status;
mutex_unlock(&slave->bus->bus_lock);
}

1
drivers/soundwire/slave.c
View File

@ -46,6 +46,7 @@ static int sdw_slave_add(struct sdw_bus *bus,
slave->dev.of_node = of_node_get(to_of_node(fwnode));
slave->bus = bus;
slave->status = SDW_SLAVE_UNATTACHED;
init_completion(&slave->enumeration_complete);
slave->dev_num = 0;
init_completion(&slave->probe_complete);
slave->probed = false;