From b7e32bef4ae5f9149276203564b7911fac466588 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= Date: Wed, 2 Jun 2021 10:38:11 +0200 Subject: drm: Add a prefetching memcpy_from_wc MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Reading out of write-combining mapped memory is typically very slow since the CPU doesn't prefetch. However some archs have special instructions to do this. So add a best-effort memcpy_from_wc taking dma-buf-map pointer arguments that attempts to use a fast prefetching memcpy and otherwise falls back to ordinary memcopies, taking the iomem tagging into account. The code is largely copied from i915_memcpy_from_wc. Cc: Daniel Vetter Cc: Christian König Suggested-by: Daniel Vetter Signed-off-by: Thomas Hellström Acked-by: Christian König Acked-by: Daniel Vetter Link: https://lore.kernel.org/r/20210602083818.241793-5-thomas.hellstrom@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20210602083818.241793-5-thomas.hellstrom@linux.intel.com --- Documentation/gpu/drm-mm.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'Documentation/gpu/drm-mm.rst') diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst index 21be6deadc12..d5a73fa2c9ef 100644 --- a/Documentation/gpu/drm-mm.rst +++ b/Documentation/gpu/drm-mm.rst @@ -469,8 +469,8 @@ DRM MM Range Allocator Function References .. kernel-doc:: drivers/gpu/drm/drm_mm.c :export: -DRM Cache Handling -================== +DRM Cache Handling and Fast WC memcpy() +======================================= .. kernel-doc:: drivers/gpu/drm/drm_cache.c :export: -- cgit v1.2.3