Re: [PATCH v3 08/12] drm/ttm: Use drm_memcpy_from_wc_dbm for TTM bo moves

["Christian König" <christian.koenig@amd.com>]

Am 21.05.21 um 17:32 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>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/ttm/ttm_bo_util.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index 912cbe8e60a2..4a7d3d672f9a 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>
> @@ -91,6 +92,7 @@ void ttm_move_memcpy(struct ttm_buffer_object *bo,
>   	const struct ttm_kmap_iter_ops *src_ops = src_iter->ops;
>   	struct ttm_tt *ttm = bo->ttm;
>   	struct dma_buf_map src_map, dst_map;
> +	bool wc_memcpy;
>   	pgoff_t i;
>   
>   	/* Single TTM move. NOP */
> @@ -114,11 +116,16 @@ void ttm_move_memcpy(struct ttm_buffer_object *bo,
>   		return;
>   	}
>   
> +	wc_memcpy = ((!src_ops->maps_tt || ttm->caching != ttm_cached) &&
> +		     drm_has_memcpy_from_wc());
> +
>   	for (i = 0; i < dst_mem->num_pages; ++i) {
>   		dst_ops->map_local(dst_iter, &dst_map, i);
>   		src_ops->map_local(src_iter, &src_map, i);
>   
> -		if (!src_map.is_iomem && !dst_map.is_iomem) {
> +		if (wc_memcpy) {
> +			drm_memcpy_from_wc_dbm(&dst_map, &src_map, PAGE_SIZE);
> +		} else if (!src_map.is_iomem && !dst_map.is_iomem) {
>   			memcpy(dst_map.vaddr, src_map.vaddr, PAGE_SIZE);
>   		} else if (!src_map.is_iomem) {
>   			dma_buf_map_memcpy_to(&dst_map, src_map.vaddr,