From: Rob Clark <robdcl...@chromium.org> drm_cflush_pages() is no-op on arm/arm64. But instead we can use dma_sync API.
Fixes failures w/ vgem_test. Signed-off-by: Rob Clark <robdcl...@chromium.org> --- An alternative approach to the series[1] I sent yesterday On the plus side, it keeps the WC buffers and avoids any drm core changes. On the minus side, I don't think it will work (at least on arm64) prior to v5.0[2], so the fix can't be backported very far. [1] https://patchwork.freedesktop.org/series/63771/ [2] depends on 356da6d0cde3323236977fce54c1f9612a742036 drivers/gpu/drm/vgem/vgem_drv.c | 130 ++++++++++++++++++++------------ 1 file changed, 83 insertions(+), 47 deletions(-) diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c index 76d95b5e289c..6c9b5e20b3d4 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.c +++ b/drivers/gpu/drm/vgem/vgem_drv.c @@ -47,10 +47,16 @@ static struct vgem_device { struct platform_device *platform; } *vgem_device; +static void sync_and_unpin(struct drm_vgem_gem_object *bo); +static struct page **pin_and_sync(struct drm_vgem_gem_object *bo); + static void vgem_gem_free_object(struct drm_gem_object *obj) { struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj); + if (!obj->import_attach) + sync_and_unpin(vgem_obj); + kvfree(vgem_obj->pages); mutex_destroy(&vgem_obj->pages_lock); @@ -78,40 +84,15 @@ static vm_fault_t vgem_gem_fault(struct vm_fault *vmf) return VM_FAULT_SIGBUS; mutex_lock(&obj->pages_lock); + if (!obj->pages) + pin_and_sync(obj); if (obj->pages) { get_page(obj->pages[page_offset]); vmf->page = obj->pages[page_offset]; ret = 0; } mutex_unlock(&obj->pages_lock); - if (ret) { - struct page *page; - - page = shmem_read_mapping_page( - file_inode(obj->base.filp)->i_mapping, - page_offset); - if (!IS_ERR(page)) { - vmf->page = page; - ret = 0; - } else switch (PTR_ERR(page)) { - case -ENOSPC: - case -ENOMEM: - ret = VM_FAULT_OOM; - break; - case -EBUSY: - ret = VM_FAULT_RETRY; - break; - case -EFAULT: - case -EINVAL: - ret = VM_FAULT_SIGBUS; - break; - default: - WARN_ON(PTR_ERR(page)); - ret = VM_FAULT_SIGBUS; - break; - } - } return ret; } @@ -277,32 +258,93 @@ static const struct file_operations vgem_driver_fops = { .release = drm_release, }; -static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo) +/* Called under pages_lock, except in free path (where it can't race): */ +static void sync_and_unpin(struct drm_vgem_gem_object *bo) { - mutex_lock(&bo->pages_lock); - if (bo->pages_pin_count++ == 0) { - struct page **pages; + struct drm_device *dev = bo->base.dev; + + if (bo->table) { + dma_sync_sg_for_cpu(dev->dev, bo->table->sgl, + bo->table->nents, DMA_BIDIRECTIONAL); + sg_free_table(bo->table); + kfree(bo->table); + bo->table = NULL; + } + + if (bo->pages) { + drm_gem_put_pages(&bo->base, bo->pages, true, true); + bo->pages = NULL; + } +} + +static struct page **pin_and_sync(struct drm_vgem_gem_object *bo) +{ + struct drm_device *dev = bo->base.dev; + int npages = bo->base.size >> PAGE_SHIFT; + struct page **pages; + struct sg_table *sgt; + + WARN_ON(!mutex_is_locked(&bo->pages_lock)); + + pages = drm_gem_get_pages(&bo->base); + if (IS_ERR(pages)) { + bo->pages_pin_count--; + mutex_unlock(&bo->pages_lock); + return pages; + } - pages = drm_gem_get_pages(&bo->base); - if (IS_ERR(pages)) { - bo->pages_pin_count--; - mutex_unlock(&bo->pages_lock); - return pages; - } + sgt = drm_prime_pages_to_sg(pages, npages); + if (IS_ERR(sgt)) { + dev_err(dev->dev, + "failed to allocate sgt: %ld\n", + PTR_ERR(bo->table)); + drm_gem_put_pages(&bo->base, pages, false, false); + mutex_unlock(&bo->pages_lock); + return ERR_CAST(bo->table); + } + + /* + * Flush the object from the CPU cache so that importers + * can rely on coherent indirect access via the exported + * dma-address. + */ + dma_sync_sg_for_device(dev->dev, sgt->sgl, + sgt->nents, DMA_BIDIRECTIONAL); + + bo->pages = pages; + bo->table = sgt; + + return pages; +} + +static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo) +{ + struct page **pages; - bo->pages = pages; + mutex_lock(&bo->pages_lock); + if (bo->pages_pin_count++ == 0 && !bo->pages) { + pages = pin_and_sync(bo); + } else { + WARN_ON(!bo->pages); + pages = bo->pages; } mutex_unlock(&bo->pages_lock); - return bo->pages; + return pages; } static void vgem_unpin_pages(struct drm_vgem_gem_object *bo) { + /* + * We shouldn't hit this for imported bo's.. in the import + * case we don't own the scatter-table + */ + WARN_ON(bo->base.import_attach); + mutex_lock(&bo->pages_lock); if (--bo->pages_pin_count == 0) { - drm_gem_put_pages(&bo->base, bo->pages, true, true); - bo->pages = NULL; + WARN_ON(!bo->table); + sync_and_unpin(bo); } mutex_unlock(&bo->pages_lock); } @@ -310,18 +352,12 @@ static void vgem_unpin_pages(struct drm_vgem_gem_object *bo) static int vgem_prime_pin(struct drm_gem_object *obj) { struct drm_vgem_gem_object *bo = to_vgem_bo(obj); - long n_pages = obj->size >> PAGE_SHIFT; struct page **pages; pages = vgem_pin_pages(bo); if (IS_ERR(pages)) return PTR_ERR(pages); - /* Flush the object from the CPU cache so that importers can rely - * on coherent indirect access via the exported dma-address. - */ - drm_clflush_pages(pages, n_pages); - return 0; } -- 2.21.0
