drm/amdgpu: nuke the ih reentrant lock

Interrupts on are non-reentrant on linux. This is just an ancient
leftover from radeon where irq processing was kicked of from different
places.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -3284,7 +3284,6 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 
 	/* mutex initialization are all done here so we
 	 * can recall function without having locking issues */
-	atomic_set(&adev->irq.ih.lock, 0);
 	mutex_init(&adev->firmware.mutex);
 	mutex_init(&adev->pm.mutex);
 	mutex_init(&adev->gfx.gpu_clock_mutex);

drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c

@@ -228,10 +228,6 @@ int amdgpu_ih_process(struct amdgpu_device *adev, struct amdgpu_ih_ring *ih)
 	wptr = amdgpu_ih_get_wptr(adev, ih);
 
 restart_ih:
-	/* is somebody else already processing irqs? */
-	if (atomic_xchg(&ih->lock, 1))
-		return IRQ_NONE;
-
 	DRM_DEBUG("%s: rptr %d, wptr %d\n", __func__, ih->rptr, wptr);
 
 	/* Order reading of wptr vs. reading of IH ring data */
@@ -244,7 +240,6 @@ int amdgpu_ih_process(struct amdgpu_device *adev, struct amdgpu_ih_ring *ih)
 
 	amdgpu_ih_set_rptr(adev, ih);
 	wake_up_all(&ih->wait_process);
-	atomic_set(&ih->lock, 0);
 
 	/* make sure wptr hasn't changed while processing */
 	wptr = amdgpu_ih_get_wptr(adev, ih);

drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h

@@ -64,7 +64,6 @@ struct amdgpu_ih_ring {
 
 	bool                    enabled;
 	unsigned		rptr;
-	atomic_t		lock;
 	struct amdgpu_ih_regs	ih_regs;
 
 	/* For waiting on IH processing at checkpoint. */