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

Yury Norov
2026-04-24T00:52:26Z

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>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
index d9e283f3b57d..47d52cb2f1ba 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
@@ -194,14 +194,11 @@ 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