soundwire: intel_bus_common: prevent peripheral interrupts during bus…

… config

There is an potential deadlock on Intel platforms with the following
scenario:

a) the bank switch starts and the msg->lock is taken

b) an interrupt happens and the workqueue schedules a read from
IntStat0 register, which is blocked by the msg->lock

c) the manager writes the bank switch command, which is blocked by the
read that won't go out.

b) is blocked by a) and c) is blocked by b).

This patch suggests disabling the peripheral interrupts temporarily
during sync_arm/sync_go sequences used by the bank switch.

FIXME: What happens if there's already a work scheduled?

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

drivers/soundwire/intel_bus_common.c

@@ -238,6 +238,8 @@ int intel_pre_bank_switch(struct sdw_intel *sdw)
 	if (!bus->multi_link)
 		return 0;
 
+	sdw_cdns_enable_slave_alerts(cdns, false);
+
 	sdw_intel_sync_arm(sdw);
 
 	return 0;
@@ -276,5 +278,7 @@ int intel_post_bank_switch(struct sdw_intel *sdw)
 	if (ret < 0)
 		dev_err(sdw->cdns.dev, "Post bank switch failed: %d\n", ret);
 
+	sdw_cdns_enable_slave_alerts(cdns, true);
+
 	return ret;
 }