<html><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body text="#000000" bgcolor="#ffffff"> <p><span style="font-size:12.0pt;font-family:"Aptos",sans-serif; mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Aptos;mso-fareast-theme-font: minor-latin;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;mso-ansi-language:EN-US;mso-fareast-language: EN-US;mso-bidi-language:AR-SA">Reviewed-by: Sunil Khatri <a class="moz-txt-link-rfc2396E" href="mailto:sunil.khatri@amd.com"><sunil.khatri@amd.com></a><br> </span></p> <div class="moz-cite-prefix">On 10/8/2024 11:41 PM, Christian König wrote:<br> </div> <blockquote type="cite" cite="mid:20241008181134.1350-1-christian.koenig@amd.com"> <pre class="moz-quote-pre" wrap="">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. Signed-off-by: Christian König <a class="moz-txt-link-rfc2396E" href="mailto:christian.koenig@amd.com"><christian.koenig@amd.com></a> --- drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c | 10 +++------- drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h | 11 ++++------- 2 files changed, 7 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c index 910293664902..a6e28fe3f8d6 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c @@ -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 = &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 = 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; diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h index 574336d6714a..36fc9578c53c 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h @@ -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; </pre> </blockquote> </body> </html>