[PATCH v6 4/8] drm/amdgpu: give ttm entities access to all the sdma scheds

From: Pierre-Eric Pelloux-Prayer

Date: Wed Apr 08 2026 - 06:13:38 EST


With this change we now have as many clear and move entities as we
have sdma engines (limited to TTM_NUM_MOVE_FENCES).

To enable load-balancing this patch gives access to all sdma
schedulers to all entities, except default_entity which has no
use for multiple schedulers.

---
v6: add comment
---

Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@xxxxxxx>
Reviewed-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 5d10c08fd989..7b92f240eea7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -2349,8 +2349,6 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
return;

if (enable) {
- struct drm_gpu_scheduler *sched;
-
if (!adev->mman.num_buffer_funcs_scheds) {
dev_warn(adev->dev, "Not enabling DMA transfers for in kernel use");
return;
@@ -2358,11 +2356,11 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)

num_clear_entities = MIN(adev->mman.num_buffer_funcs_scheds, TTM_NUM_MOVE_FENCES);
num_move_entities = MIN(adev->mman.num_buffer_funcs_scheds, TTM_NUM_MOVE_FENCES);
- sched = adev->mman.buffer_funcs_scheds[0];
+ /* default_entity doesn't need multiple schedulers so pass only 1. */
r = amdgpu_ttm_buffer_entity_init(&adev->mman.gtt_mgr,
&adev->mman.default_entity,
DRM_SCHED_PRIORITY_KERNEL,
- &sched, 1, 0);
+ adev->mman.buffer_funcs_scheds, 1, 0);
if (r < 0) {
dev_err(adev->dev,
"Failed setting up TTM entity (%d)\n", r);
@@ -2380,8 +2378,11 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)

for (i = 0; i < num_clear_entities; i++) {
r = amdgpu_ttm_buffer_entity_init(
- &adev->mman.gtt_mgr, &adev->mman.clear_entities[i],
- DRM_SCHED_PRIORITY_NORMAL, &sched, 1, 1);
+ &adev->mman.gtt_mgr,
+ &adev->mman.clear_entities[i],
+ DRM_SCHED_PRIORITY_NORMAL,
+ adev->mman.buffer_funcs_scheds,
+ adev->mman.num_buffer_funcs_scheds, 1);

if (r < 0) {
for (j = 0; j < i; j++)
@@ -2400,7 +2401,9 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
r = amdgpu_ttm_buffer_entity_init(
&adev->mman.gtt_mgr,
&adev->mman.move_entities[i],
- DRM_SCHED_PRIORITY_NORMAL, &sched, 1, 2);
+ DRM_SCHED_PRIORITY_NORMAL,
+ adev->mman.buffer_funcs_scheds,
+ adev->mman.num_buffer_funcs_scheds, 2);

if (r < 0) {
for (j = 0; j < i; j++)
--
2.43.0