[PATCH 3/8] soundwire: amd: fix work drain ordering and pm_runtime guard in remove path

[Vijendar Mukunda]

amd_sdw_manager_remove() cancelled amd_sdw_work but not
amd_sdw_irq_thread. Since amd_sdw_irq_thread() calls
schedule_work(&amd_sdw_work), an in-flight irq_thread item can
re-queue amd_sdw_work after its cancel returns, defeating the
cancellation.

Fix by calling amd_disable_sdw_interrupts() first to quiesce the
hardware IRQ source, then cancel_work_sync() for amd_sdw_irq_thread,
then cancel_work_sync() for amd_sdw_work. The existing
cancel_work_sync(amd_sdw_work) is also moved to after
amd_disable_sdw_interrupts() so that any work item queued between the
old cancel position and the interrupt disable cannot escape draining.

synchronize_irq() is deliberately not used before the
cancel_work_sync() calls. Once SoundWire interrupts are masked, no new
IRQ deliveries can occur. An IRQ handler already in flight may still
queue amd_sdw_irq_thread, so cancel_work_sync() is used to drain both
amd_sdw_irq_thread and any amd_sdw_work items it may have scheduled.
This fully quiesces the driver workqueues, making synchronize_irq()
unnecessary.

Also guard pm_runtime_disable() so it is only called when runtime PM
was actually enabled. amd_sdw_manager_start() calls pm_runtime_enable()
only at the very end, after several fallible hardware init steps. If
sdw_amd_startup() fails mid-loop (one manager started, the next fails
before pm_runtime_enable()), sdw_amd_exit() triggers
platform_device_unregister() for all managers. Calling
pm_runtime_disable() on the partially-started manager finds
disable_depth already at its initial value of 1, silently increments it
to 2 and returns without a warning, so a later pm_runtime_enable() would
only bring it back to 1 and leave runtime PM disabled. Use
pm_runtime_enabled() to skip the call when it was never paired with an
enable.

Fixes: f93b697ed98e ("soundwire: amd: cancel pending slave status handling workqueue during remove sequence")
Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda@xxxxxxx>
---
 drivers/soundwire/amd_manager.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/soundwire/amd_manager.c b/drivers/soundwire/amd_manager.c
index a57b59609bfe..bbe1e73ed255 100644
--- a/drivers/soundwire/amd_manager.c
+++ b/drivers/soundwire/amd_manager.c
@@ -1172,9 +1172,11 @@ static void amd_sdw_manager_remove(struct platform_device *pdev)
 	struct amd_sdw_manager *amd_manager = dev_get_drvdata(&pdev->dev);
 	int ret;
 
-	pm_runtime_disable(&pdev->dev);
-	cancel_work_sync(&amd_manager->amd_sdw_work);
+	if (pm_runtime_enabled(&pdev->dev))
+		pm_runtime_disable(&pdev->dev);
 	amd_disable_sdw_interrupts(amd_manager);
+	cancel_work_sync(&amd_manager->amd_sdw_irq_thread);
+	cancel_work_sync(&amd_manager->amd_sdw_work);
 	sdw_bus_master_delete(&amd_manager->bus);
 	ret = amd_disable_sdw_manager(amd_manager);
 	if (ret)
-- 
2.48.1