Commit 57e233c3 authored by Boris Brezillon's avatar Boris Brezillon Committed by Steven Price
Browse files

drm/panthor: Fix a race between the reset and suspend path 



If a reset is scheduled when the suspend happens, we drop the
reset-pending info on the floor assuming the resume will fix things,
but the resume logic might try a fast reset. If we're lucky, the
fast reset fails and we fallback to a slow reset, but if the FW was
corrupted in a way that makes it partially functional (it boots but
doesn't quite do what it's expected to do), we won't notice immediately
that things are not working correctly, leading to a new reset further
down the road.

Fixes: 5fe909ca ("drm/panthor: Add the device logical block")
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: default avatarLiviu Dudau <liviu.dudau@arm.com>
Reviewed-by: default avatarSteven Price <steven.price@arm.com>
Signed-off-by: default avatarSteven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241217092457.1582053-1-boris.brezillon@collabora.com
parent 573b73e5

drivers/gpu/drm/panthor/panthor_device.c

+12 −10
Original line number Diff line number Diff line
@@ -128,14 +128,11 @@ static void panthor_device_reset_work(struct work_struct *work) 
	struct panthor_device *ptdev = container_of(work, struct panthor_device, reset.work);

	int ret = 0, cookie;



	if (atomic_read(&ptdev->pm.state) != PANTHOR_DEVICE_PM_STATE_ACTIVE) {

		/*

		 * No need for a reset as the device has been (or will be)

		 * powered down

	/* If the device is entering suspend, we don't reset. A slow reset will

	 * be forced at resume time instead.

	 */

		atomic_set(&ptdev->reset.pending, 0);

	if (atomic_read(&ptdev->pm.state) != PANTHOR_DEVICE_PM_STATE_ACTIVE)

		return;

	}



	if (!drm_dev_enter(&ptdev->base, &cookie))

		return;
@@ -477,6 +474,14 @@ int panthor_device_resume(struct device *dev) 


	if (panthor_device_is_initialized(ptdev) &&

	    drm_dev_enter(&ptdev->base, &cookie)) {

		/* If there was a reset pending at the time we suspended the

		 * device, we force a slow reset.

		 */

		if (atomic_read(&ptdev->reset.pending)) {

			ptdev->reset.fast = false;

			atomic_set(&ptdev->reset.pending, 0);

		}



		ret = panthor_device_resume_hw_components(ptdev);

		if (ret && ptdev->reset.fast) {

			drm_err(&ptdev->base, "Fast reset failed, trying a slow reset");
@@ -493,9 +498,6 @@ int panthor_device_resume(struct device *dev) 
			goto err_suspend_devfreq;

	}



	if (atomic_read(&ptdev->reset.pending))

		queue_work(ptdev->reset.wq, &ptdev->reset.work);



	/* Clear all IOMEM mappings pointing to this device after we've

	 * resumed. This way the fake mappings pointing to the dummy pages

	 * are removed and the real iomem mapping will be restored on next