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

Fixes: 6e2d3b3e8589 ("drm/panthor: Add support for atomic page table updates")
Signed-off-by: Boris Brezillon <[email protected]>
Reviewed-by: Liviu Dudau <[email protected]>
Reviewed-by: Chia-I Wu <[email protected]>
---
 drivers/gpu/drm/panthor/panthor_mmu.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c 
b/drivers/gpu/drm/panthor/panthor_mmu.c
index 3644af1a8e56..493e6428d478 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -588,14 +588,27 @@ 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 a lock pending. */
+               ret = as_send_cmd_and_wait(ptdev, vm->as.id, AS_COMMAND_UNLOCK);
+               if (ret)
+                       return ret;
+
+               vm->locked_region.start = 0;
+               vm->locked_region.size = 0;
+       }
+
        /* If the slot is going to be used immediately, don't bother changing
         * the config.
         */
-- 
2.51.1

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