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>

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index a2267c3..ea04cf5 100644 (file)
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -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;

diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c
index e767a78..aace57f 100644 (file)
--- a/drivers/soundwire/slave.c
+++ b/drivers/soundwire/slave.c
@@ -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;