On 11/3/25 23:23, Timur Kristóf wrote:
> GART contains some pages in its address space that come before
> the GTT and are used for BO copies.
>
> Instead of hardcoding the size of the GART space before GTT,
> make it a field in the amdgpu_gmc struct. This allows us to map
> more things in GART before GTT.
>
> Split this into a separate patch to make it easier to bisect,
> in case there are any errors in the future.
>
> Signed-off-by: Timur Kristóf <[email protected]>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 2 ++
> drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h | 1 +
> drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c | 2 +-
> 3 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> index 97b562a79ea8..bf31bd022d6d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> @@ -325,6 +325,8 @@ void amdgpu_gmc_gart_location(struct amdgpu_device *adev,
> struct amdgpu_gmc *mc,
> break;
> }
>
> + mc->num_gart_pages_before_gtt =
> + AMDGPU_GTT_MAX_TRANSFER_SIZE * AMDGPU_GTT_NUM_TRANSFER_WINDOWS;
> mc->gart_start &= ~(four_gb - 1);
> mc->gart_end = mc->gart_start + mc->gart_size - 1;
> dev_info(adev->dev, "GART: %lluM 0x%016llX - 0x%016llX\n",
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> index 55097ca10738..568eed3eb557 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> @@ -266,6 +266,7 @@ struct amdgpu_gmc {
> u64 fb_end;
> unsigned vram_width;
> u64 real_vram_size;
> + u32 num_gart_pages_before_gtt;
> int vram_mtrr;
> u64 mc_mask;
> const struct firmware *fw; /* MC firmware */
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> index 0760e70402ec..4c2563a70c2b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> @@ -283,7 +283,7 @@ int amdgpu_gtt_mgr_init(struct amdgpu_device *adev,
> uint64_t gtt_size)
>
> ttm_resource_manager_init(man, &adev->mman.bdev, gtt_size);
>
> - start = AMDGPU_GTT_MAX_TRANSFER_SIZE * AMDGPU_GTT_NUM_TRANSFER_WINDOWS;
> + start = adev->gmc.num_gart_pages_before_gtt;
I would prefer that we have a single function which returns the number of GART
pages we need before the dynamic GTT mapping.
But let me see how Pierre-Eric solved this first.
Regards,
Christian.
> size = (adev->gmc.gart_size >> PAGE_SHIFT) - start;
> drm_mm_init(&mgr->mm, start, size);
> spin_lock_init(&mgr->lock);
