On 5/21/21 10:10 AM, Christian König wrote:
Am 20.05.21 um 17:09 schrieb Thomas Hellström:
Use fast wc memcpy for reading out of wc memory for TTM bo moves.
Cc: Dave Airlie airlied@gmail.com Cc: Christian König christian.koenig@amd.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Thomas Hellström thomas.hellstrom@linux.intel.com
Oh, yes I really wanted to have that in TTM for quite some time.
We should use it for swap copy from WC as well IMO. A todo-task for somebody.
But I'm wondering if we shouldn't fix the memremap stuff first.
Using memremap all over is a fairly big change probably with lots of opinions involved all over the place. What I can do for now is to add a dma_buf_map interface to the memcpy itself, to move the aliasing out of TTM to the arch specific code that knows what it's doing?
/Thomas
Christian.
drivers/gpu/drm/ttm/ttm_bo_util.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c index bad9b16e96ba..919ee03f7eb3 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -31,6 +31,7 @@ #include <drm/ttm/ttm_bo_driver.h> #include <drm/ttm/ttm_placement.h> +#include <drm/drm_memcpy.h> #include <drm/drm_vma_manager.h> #include <linux/dma-buf-map.h> #include <linux/io.h> @@ -185,6 +186,7 @@ void ttm_move_memcpy(struct ttm_buffer_object *bo, struct ttm_resource *old_mem = &bo->mem; struct ttm_resource_manager *old_man = ttm_manager_type(bdev, old_mem->mem_type); struct dma_buf_map old_map, new_map; + bool wc_memcpy; pgoff_t i; /* Single TTM move. NOP */ @@ -208,11 +210,25 @@ void ttm_move_memcpy(struct ttm_buffer_object *bo, return; } + wc_memcpy = ((!old_man->use_tt || bo->ttm->caching != ttm_cached) && + drm_has_memcpy_from_wc());
+ /* + * We use some nasty aliasing for drm_memcpy_from_wc, but assuming + * that we can move to memremapping in the not too distant future, + * reduce the fragility for now with a build assert. + */ + BUILD_BUG_ON(offsetof(typeof(old_map), vaddr) != + offsetof(typeof(old_map), vaddr_iomem));
for (i = 0; i < new_mem->num_pages; ++i) { new_iter->ops->kmap_local(new_iter, &new_map, i); old_iter->ops->kmap_local(old_iter, &old_map, i); - if (!old_map.is_iomem && !new_map.is_iomem) { + if (wc_memcpy) { + drm_memcpy_from_wc(new_map.vaddr, old_map.vaddr, + PAGE_SIZE); + } else if (!old_map.is_iomem && !new_map.is_iomem) { memcpy(new_map.vaddr, old_map.vaddr, PAGE_SIZE); } else if (!old_map.is_iomem) { dma_buf_map_memcpy_to(&new_map, old_map.vaddr,