On Wed, 2025-10-29 at 11:00 +0100, Christian König wrote: > On 10/28/25 23:06, 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. > > Pierre-Eric has been working on something similar. > > On the newer HW generations we need more transfer windows since we > want to utilize more DMA engines for copies and clears. > > My suggestion is that we just make AMDGPU_GTT_NUM_TRANSFER_WINDOWS > depend on adev and so the HW generation and then reserve one extra > transfer window for this workaround on SI.
I think the best would be to leave this patch as-is to avoid conflicts with Pierre-Eric's work. After that work lands, we can revisit this workaround. Does that sound reasonable to you? > > Regards, > Christian. > > > > > 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; > > size = (adev->gmc.gart_size >> PAGE_SHIFT) - start; > > drm_mm_init(&mgr->mm, start, size); > > spin_lock_init(&mgr->lock);
