From: Timur Kristóf Date: Sat, 18 Apr 2026 21:49:30 +0000 (+0200) Subject: drm/amdgpu/gmc: Fix AMDGPU_GART_PLACEMENT_LOW to not overlap with VRAM X-Git-Tag: v7.1-rc2~7^2~1^2~44 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=36d65da7570bf72ce28504fa9a81abfc728e6d96;p=thirdparty%2Flinux.git drm/amdgpu/gmc: Fix AMDGPU_GART_PLACEMENT_LOW to not overlap with VRAM When the GART placement is set to AMDGPU_GART_PLACEMENT_LOW: Make sure that GART does not overlap with VRAM when VRAM is configured to be in the low address space. Solve this according to the following logic: - When GART fits before VRAM, use zero address for GART - Otherwise, put GART after the end of VRAM, aligned to 4 GiB Previously, I had assumed this was not possible so it was OK to not handle it, but now we got a report from a user who has a board that is configured this way. Fixes: 917f91d8d8e8 ("drm/amdgpu/gmc: add a way to force a particular placement for GART") Signed-off-by: Timur Kristóf Reviewed-by: Christian König Signed-off-by: Alex Deucher (cherry picked from commit 3d9de5d86a1658cadb311461b001eb1df67263ad) --- diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c index 285e217fba04..3d9497d121ca 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c @@ -314,7 +314,10 @@ void amdgpu_gmc_gart_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc, mc->gart_start = max_mc_address - mc->gart_size + 1; break; case AMDGPU_GART_PLACEMENT_LOW: - mc->gart_start = 0; + if (size_bf >= mc->gart_size) + mc->gart_start = 0; + else + mc->gart_start = ALIGN(mc->fb_end, four_gb); break; case AMDGPU_GART_PLACEMENT_BEST_FIT: default: