Commit 57e92d99 authored by Christian König's avatar Christian König Committed by Alex Deucher
Browse files

drm/amdgpu: drop volatile from ring buffer 



Volatile only prevents the compiler from re-ordering reads and writes.
Since we always only modify the ring buffer from one CPU thread and have
an explicit barrier before signaling the HW this should have no effect at
all and just prevents compiler optimisations.

While at it drop the local variables as well.

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarSunil Khatri <sunil.khatri@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent dac64cb3

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

+3 −7
Original line number Diff line number Diff line
@@ -109,21 +109,17 @@ int amdgpu_ring_alloc(struct amdgpu_ring *ring, unsigned int ndw) 
void amdgpu_ring_insert_nop(struct amdgpu_ring *ring, uint32_t count)

{

	uint32_t occupied, chunk1, chunk2;

	uint32_t *dst;



	occupied = ring->wptr & ring->buf_mask;

	dst = (void *)&ring->ring[occupied];

	chunk1 = ring->buf_mask + 1 - occupied;

	chunk1 = (chunk1 >= count) ? count : chunk1;

	chunk2 = count - chunk1;



	if (chunk1)

		memset32(dst, ring->funcs->nop, chunk1);

		memset32(&ring->ring[occupied], ring->funcs->nop, chunk1);



	if (chunk2) {

		dst = (void *)ring->ring;

		memset32(dst, ring->funcs->nop, chunk2);

	}

	if (chunk2)

		memset32(ring->ring, ring->funcs->nop, chunk2);



	ring->wptr += count;

	ring->wptr &= ring->ptr_mask;

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

+4 −7
Original line number Diff line number Diff line
@@ -246,7 +246,7 @@ struct amdgpu_ring { 
	struct drm_gpu_scheduler	sched;



	struct amdgpu_bo	*ring_obj;

	volatile uint32_t	*ring;

	uint32_t		*ring;

	unsigned		rptr_offs;

	u64			rptr_gpu_addr;

	volatile u32		*rptr_cpu_addr;
@@ -288,7 +288,7 @@ struct amdgpu_ring { 
	u64			cond_exe_gpu_addr;

	volatile u32		*cond_exe_cpu_addr;

	unsigned int		set_q_mode_offs;

	volatile u32		*set_q_mode_ptr;

	u32			*set_q_mode_ptr;

	u64			set_q_mode_token;

	unsigned		vm_hub;

	unsigned		vm_inv_eng;
@@ -386,10 +386,8 @@ static inline void amdgpu_ring_write_multiple(struct amdgpu_ring *ring, 
					      void *src, int count_dw)

{

	unsigned occupied, chunk1, chunk2;

	void *dst;



	occupied = ring->wptr & ring->buf_mask;

	dst = (void *)&ring->ring[occupied];

	chunk1 = ring->buf_mask + 1 - occupied;

	chunk1 = (chunk1 >= count_dw) ? count_dw : chunk1;

	chunk2 = count_dw - chunk1;
@@ -397,12 +395,11 @@ static inline void amdgpu_ring_write_multiple(struct amdgpu_ring *ring, 
	chunk2 <<= 2;



	if (chunk1)

		memcpy(dst, src, chunk1);

		memcpy(&ring->ring[occupied], src, chunk1);



	if (chunk2) {

		src += chunk1;

		dst = (void *)ring->ring;

		memcpy(dst, src, chunk2);

		memcpy(ring->ring, src, chunk2);

	}



	ring->wptr += count_dw;