[PATCH v2] drm/amdgpu: use bitmap_clear() in amdgpu_amdkfd_device_init()

[Yury Norov <ynorov@nvidia.com>]

The bitmap_clear() works OK with both compile- and runtime nbits. But the
comment says it doesn't work, and opencodes the call for nothing.
Drop the misleading comment, and use bitmap_clear() as it should.

As a side effect, the patch switches from a series of atomics to
a single non-atomic operation, which is easier on caches.

Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
v2: don't declare 'i' in the new implementation.

 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
index d9e283f3b57d..500976d9087a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
@@ -167,7 +167,6 @@ int amdgpu_amdkfd_drm_client_create(struct amdgpu_device *adev)
 
 void amdgpu_amdkfd_device_init(struct amdgpu_device *adev)
 {
-	int i;
 	int last_valid_bit;
 
 	amdgpu_amdkfd_gpuvm_init_mem_limits();
@@ -194,14 +193,11 @@ void amdgpu_amdkfd_device_init(struct amdgpu_device *adev)
 				  adev->gfx.mec_bitmap[0].queue_bitmap,
 				  AMDGPU_MAX_QUEUES);
 
-		/* According to linux/bitmap.h we shouldn't use bitmap_clear if
-		 * nbits is not compile time constant
-		 */
 		last_valid_bit = 1 /* only first MEC can have compute queues */
 				* adev->gfx.mec.num_pipe_per_mec
 				* adev->gfx.mec.num_queue_per_pipe;
-		for (i = last_valid_bit; i < AMDGPU_MAX_QUEUES; ++i)
-			clear_bit(i, gpu_resources.cp_queue_bitmap);
+		bitmap_clear(gpu_resources.cp_queue_bitmap, last_valid_bit,
+					AMDGPU_MAX_QUEUES - last_valid_bit);
 
 		amdgpu_doorbell_get_kfd_info(adev,
 				&gpu_resources.doorbell_physical_address,
-- 
2.51.0