On Tue, 18 Feb 2025 23:25:36 +0000 Adrián Larumbe <[email protected]> wrote:
> Panfrost heap BOs grow on demand when the GPU triggers a page fault after > accessing an address within the BO's virtual range. > > We still store the sgts we get back from the shmem sparse allocation function, > since it was decided management of sparse memory SGTs should be done by client > drivers rather than the shmem subsystem. > > Signed-off-by: Adrián Larumbe <[email protected]> > --- > drivers/gpu/drm/panfrost/panfrost_gem.c | 12 ++-- > drivers/gpu/drm/panfrost/panfrost_gem.h | 2 +- > drivers/gpu/drm/panfrost/panfrost_mmu.c | 85 +++++-------------------- > 3 files changed, 25 insertions(+), 74 deletions(-) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c > b/drivers/gpu/drm/panfrost/panfrost_gem.c > index 8e0ff3efede7..0cda2c4e524f 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_gem.c > +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c > @@ -40,10 +40,10 @@ static void panfrost_gem_free_object(struct > drm_gem_object *obj) > int n_sgt = bo->base.base.size / SZ_2M; > > for (i = 0; i < n_sgt; i++) { > - if (bo->sgts[i].sgl) { > - dma_unmap_sgtable(pfdev->dev, &bo->sgts[i], > + if (bo->sgts[i]) { > + dma_unmap_sgtable(pfdev->dev, bo->sgts[i], > DMA_BIDIRECTIONAL, 0); > - sg_free_table(&bo->sgts[i]); > + sg_free_table(bo->sgts[i]); > } > } > kvfree(bo->sgts); > @@ -274,7 +274,11 @@ panfrost_gem_create(struct drm_device *dev, size_t size, > u32 flags) > if (flags & PANFROST_BO_HEAP) > size = roundup(size, SZ_2M); > > - shmem = drm_gem_shmem_create(dev, size); > + if (flags & PANFROST_BO_HEAP) > + shmem = drm_gem_shmem_create_sparse(dev, size); > + else > + shmem = drm_gem_shmem_create(dev, size); > + > if (IS_ERR(shmem)) > return ERR_CAST(shmem); > > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h > b/drivers/gpu/drm/panfrost/panfrost_gem.h > index 7516b7ecf7fe..2a8d0752011e 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_gem.h > +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h > @@ -11,7 +11,7 @@ struct panfrost_mmu; > > struct panfrost_gem_object { > struct drm_gem_shmem_object base; > - struct sg_table *sgts; > + struct sg_table **sgts; I guess using an xarray here would make sense. Or maybe even an sg_append_table, since we don't expect holes in the populated pages. This makes me wonder if we really want the gem_shmem layer to automate sgt creation for sparse GEM objects. Looks like something the driver can easily optimize for its use-case.
