Commit a90def06 authored by Pierre-Louis Bossart's avatar Pierre-Louis Bossart Committed by Vinod Koul
Browse files

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: default avatarRander Wang <rander.wang@linux.intel.com>
Signed-off-by: default avatarPierre-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: default avatarVinod Koul <vkoul@kernel.org>
parent fb9469e5

drivers/soundwire/bus.c

+8 −0
Original line number Diff line number Diff line
@@ -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;

drivers/soundwire/slave.c

+1 −0
Original line number Diff line number Diff line
@@ -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;