drm/amdgpu/ttm: Consider concurrent VM flushes for buffer entities

Allow using multiple SDMA schedulers only on GPUs where
we are allowed to do concurrent VM flushes.
This consideration is necessary because all GART windows
are mapped in VMID 0 (the kernel VMID) so each buffer
entity would flush VMID 0 concurrently.

Practically this means that we can't use multiple SDMA
engines for TTM on GFX6-8 and Navi 1x.

Fixes: 01c836788b37 ("drm/amdgpu: pass all the sdma scheds to amdgpu_mman")
Fixes: e4029f7a9474 ("drm/amdgpu: only use working sdma schedulers for ttm")
Cc: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit a8171229bc836607fbc225d323ebc4d14489cfbb)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 025625e7e800fcedef5b6c714df9ea7a97e42731..eb8bbfc7e6d9b999ea772b413bb6cd814c2b5c06 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -2684,12 +2684,22 @@ void amdgpu_sdma_set_buffer_funcs_scheds(struct amdgpu_device *adev,
                return;
        }
 
-       /* Navi1x's workaround requires us to limit to a single SDMA sched
-        * for ttm.
-        */
        hub = &adev->vmhub[AMDGPU_GFXHUB(0)];
-       adev->mman.num_buffer_funcs_scheds = hub->sdma_invalidation_workaround ?
-               1 : n;
+
+       /*
+        * Allow using multiple SDMA schedulers only on GPUs where
+        * we are allowed to do concurrent VM flushes.
+        * This consideration is necessary because all GART windows
+        * are mapped in VMID 0 (the kernel VMID) so each buffer
+        * entity would flush VMID 0 concurrently.
+        *
+        * Also consider the SDMA invalidation workaround on
+        * Navi 1x GPUs, which also prevents us from using
+        * multiple SDMA engines on VMID 0 at the same time.
+        */
+       adev->mman.num_buffer_funcs_scheds =
+               (adev->vm_manager.concurrent_flush &&
+                !hub->sdma_invalidation_workaround) ? n : 1;
 }
 
 #if defined(CONFIG_DEBUG_FS)