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soundwire: bus: fix race condition with initialization_complete signaling 

Waiting for the enumeration to be complete may not be enough for a
Slave driver, there is a possible race condition between resume
operations and initializations handled in an interrupt thread, which
can results in settings not being fully restored after system or
pm_runtime resume.

This patch builds on the changes added for enumeration_complete,
init_completion() is called when the Slave device becomes UNATTACHED,
as done with enumeration_complete.

The difference with the enumeration_complete case is that complete()
is signaled after the Slave device is fully initialized after the
.update_status() callback is called.

A Slave device driver can decide to wait on either of the two
complete() cases, depending on its initialization code and
requirements.

Signed-off-by: Rander Wang <rander.wang@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200115000844.14695-4-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 18:08:37 -06:00 committed by Vinod Koul
parent fb9469e54f
commit a90def0681
2 changed files with 9 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/soundwire/bus.c
View File

@ -621,6 +621,7 @@ static void sdw_modify_slave_status(struct sdw_slave *slave,
__func__, slave->dev_num);
init_completion(&slave->enumeration_complete);
init_completion(&slave->initialization_complete);
} else if ((status == SDW_SLAVE_ATTACHED) &&
(slave->status == SDW_SLAVE_UNATTACHED)) {
@ -1025,6 +1026,7 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
{
enum sdw_slave_status prev_status;
struct sdw_slave *slave;
bool attached_initializing;
int i, ret = 0;
/* first check if any Slaves fell off the bus */
@ -1070,6 +1072,8 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
if (!slave)
continue;
attached_initializing = false;
switch (status[i]) {
case SDW_SLAVE_UNATTACHED:
if (slave->status == SDW_SLAVE_UNATTACHED)
@ -1096,6 +1100,8 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
if (prev_status == SDW_SLAVE_ALERT)
break;
attached_initializing = true;
ret = sdw_initialize_slave(slave);
if (ret)
dev_err(bus->dev,
@ -1114,6 +1120,8 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
if (ret)
dev_err(slave->bus->dev,
"Update Slave status failed:%d\n", ret);
if (attached_initializing)
complete(&slave->initialization_complete);
}
return ret;

1
drivers/soundwire/slave.c
View File

@ -47,6 +47,7 @@ static int sdw_slave_add(struct sdw_bus *bus,
slave->bus = bus;
slave->status = SDW_SLAVE_UNATTACHED;
init_completion(&slave->enumeration_complete);
init_completion(&slave->initialization_complete);
slave->dev_num = 0;
init_completion(&slave->probe_complete);
slave->probed = false;