Re: [PATCH] drm/amdgpu: use the last IB as gang leader v2

[Christian König]

Am 15.11.22 um 10:42 schrieb Christian König:
It turned out that not the last IB specified is the gang leader,
but instead the last job allocated.
This is a bit unfortunate and not very intuitive for the CS
interface, so try to fix this.

Alex could you take a look at this? I would really like to get this into 
the next -rc.

Thanks,
Christian.


Signed-off-by: Christian König <christian.koe...@amd.com>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 23 ++++++++++++++++-------
  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h |  1 +
  2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index 1bbd39b3b0fc..fbdf139cf497 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -109,6 +109,7 @@ static int amdgpu_cs_p1_ib(struct amdgpu_cs_parser *p,
                return r;
  
  	++(num_ibs[r]);
+       p->gang_leader_idx = r;
        return 0;
  }
  
@@ -300,7 +301,7 @@ static int amdgpu_cs_pass1(struct amdgpu_cs_parser *p,
                if (ret)
                        goto free_all_kdata;
        }
-       p->gang_leader = p->jobs[p->gang_size - 1];
+       p->gang_leader = p->jobs[p->gang_leader_idx];
  
  	if (p->ctx->vram_lost_counter != p->gang_leader->vram_lost_counter) {
                ret = -ECANCELED;
@@ -1194,16 +1195,18 @@ static int amdgpu_cs_sync_rings(struct amdgpu_cs_parser 
*p)
                        return r;
        }
  
-	for (i = 0; i < p->gang_size - 1; ++i) {
+       for (i = 0; i < p->gang_size; ++i) {
+               if (p->jobs[i] == leader)
+                       continue;
+
                r = amdgpu_sync_clone(&leader->sync, &p->jobs[i]->sync);
                if (r)
                        return r;
        }
  
-	r = amdgpu_ctx_wait_prev_fence(p->ctx, p->entities[p->gang_size - 1]);
+       r = amdgpu_ctx_wait_prev_fence(p->ctx, p->entities[p->gang_leader_idx]);
        if (r && r != -ERESTARTSYS)
                DRM_ERROR("amdgpu_ctx_wait_prev_fence failed.\n");
-
        return r;
  }
  
@@ -1237,9 +1240,12 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
        for (i = 0; i < p->gang_size; ++i)
                drm_sched_job_arm(&p->jobs[i]->base);
  
-	for (i = 0; i < (p->gang_size - 1); ++i) {
+       for (i = 0; i < p->gang_size; ++i) {
                struct dma_fence *fence;
  
+		if (p->jobs[i] == leader)
+                       continue;
+
                fence = &p->jobs[i]->base.s_fence->scheduled;
                r = amdgpu_sync_fence(&leader->sync, fence);
                if (r)
@@ -1275,7 +1281,10 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
        list_for_each_entry(e, &p->validated, tv.head) {
  
  		/* Everybody except for the gang leader uses READ */
-               for (i = 0; i < (p->gang_size - 1); ++i) {
+               for (i = 0; i < p->gang_size; ++i) {
+                       if (p->jobs[i] == leader)
+                               continue;
+
                        dma_resv_add_fence(e->tv.bo->base.resv,
                                           &p->jobs[i]->base.s_fence->finished,
                                           DMA_RESV_USAGE_READ);
@@ -1285,7 +1294,7 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
                e->tv.num_shared = 0;
        }
  
-	seq = amdgpu_ctx_add_fence(p->ctx, p->entities[p->gang_size - 1],
+       seq = amdgpu_ctx_add_fence(p->ctx, p->entities[p->gang_leader_idx],
                                   p->fence);
        amdgpu_cs_post_dependencies(p);
  
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h
index cbaa19b2b8a3..f80adf9069ec 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h
@@ -54,6 +54,7 @@ struct amdgpu_cs_parser {
  
  	/* scheduler job objects */
        unsigned int            gang_size;
+       unsigned int            gang_leader_idx;
        struct drm_sched_entity *entities[AMDGPU_CS_GANG_SIZE];
        struct amdgpu_job       *jobs[AMDGPU_CS_GANG_SIZE];
        struct amdgpu_job       *gang_leader;