From 79f408cc06525c6cd01d1a5bf83086a1beede49b Mon Sep 17 00:00:00 2001 From: =?utf8?q?Timur=20Krist=C3=B3f?= Date: Sat, 11 Jul 2026 13:49:58 +0200 Subject: [PATCH] drm/amdgpu/ttm: Consider concurrent VM flushes for buffer entities MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Timur Kristóf Reviewed-by: Christian König Signed-off-by: Alex Deucher (cherry picked from commit a8171229bc836607fbc225d323ebc4d14489cfbb) --- drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c index 025625e7e800..eb8bbfc7e6d9 100644 --- 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) -- 2.47.3