drm/panthor: Unlock the locked region before disabling an AS

An AS can be disabled in the middle of a VM operation (VM being
evicted from an AS slot, for instance). In that case, we need the
locked section to be unlocked before releasing the slot.

v2:
- Add an lockdep_assert_held() in panthor_mmu_as_disable()
- Collect R-bs

v3:
- Don't reset the locked_region range in the as_disable() path

Fixes: 6e2d3b3e8589 ("drm/panthor: Add support for atomic page table updates")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patch.msgid.link/20251203121750.404340-4-boris.brezillon@collabora.com

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 3644af1a8e564270eca310e81fe5ee8246a0fbf4..ca112d874ecb9b937047fddb95c9ea604b7a6e51 100644 (file)
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -588,14 +588,24 @@ static int panthor_mmu_as_enable(struct panthor_device *ptdev, u32 as_nr,
 static int panthor_mmu_as_disable(struct panthor_device *ptdev, u32 as_nr,
                                  bool recycle_slot)
 {
+       struct panthor_vm *vm = ptdev->mmu->as.slots[as_nr].vm;
        int ret;
 
+       lockdep_assert_held(&ptdev->mmu->as.slots_lock);
+
        /* Flush+invalidate RW caches, invalidate RO ones. */
        ret = panthor_gpu_flush_caches(ptdev, CACHE_CLEAN | CACHE_INV,
                                       CACHE_CLEAN | CACHE_INV, CACHE_INV);
        if (ret)
                return ret;
 
+       if (vm && vm->locked_region.size) {
+               /* Unlock the region if there's a lock pending. */
+               ret = as_send_cmd_and_wait(ptdev, vm->as.id, AS_COMMAND_UNLOCK);
+               if (ret)
+                       return ret;
+       }
+
        /* If the slot is going to be used immediately, don't bother changing
         * the config.
         */