On Mon, Feb 28, 2022 at 11:48:58PM -0800, Lucas De Marchi wrote:
On Tue, Feb 22, 2022 at 08:22:01PM +0530, Balasubramani Vivekanandan wrote:
Fast copy using non-temporal instructions for x86 currently exists at two
locations. One is implemented in i915 driver at i915/i915_memcpy.c and
another copy at drm_cache.c. The plan is to remove the duplicate
implementation in i915 driver and use the functions from drm_cache.c.
A variant of drm_memcpy_from_wc() is added in drm_cache.c which accepts
address as argument instead of iosys_map for destination. It is a very
common scenario in i915 to copy from a WC memory type, which may be an
io memory or a system memory to a destination address pointing to system
memory. To avoid the overhead of creating iosys_map type for the
destination, new variant is created to accept the address directly.
Also a new function is exported in drm_cache.c to find if the fast copy
is supported by the platform or not. It is required for i915.
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Thomas Hellstr_m <thomas.hellstrom@xxxxxxxxxxxxxxx>
Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@xxxxxxxxx>
---
drivers/gpu/drm/drm_cache.c | 54 +++++++++++++++++++++++++++++++++++++
include/drm/drm_cache.h | 3 +++
2 files changed, 57 insertions(+)
diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
index a21c1350eb09..eb0bcd33665e 100644
--- a/drivers/gpu/drm/drm_cache.c
+++ b/drivers/gpu/drm/drm_cache.c
@@ -358,6 +358,54 @@ void drm_memcpy_from_wc(struct iosys_map *dst,
}
EXPORT_SYMBOL(drm_memcpy_from_wc);
+/**
+ * drm_memcpy_from_wc_vaddr - Perform the fastest available memcpy from a source
+ * that may be WC.
.... to a destination in system memory.
+ * @dst: The destination pointer
+ * @src: The source pointer
+ * @len: The size of the area to transfer in bytes
+ *
+ * Same as drm_memcpy_from_wc except destination is accepted as system memory
+ * address. Useful in situations where passing destination address as iosys_map
+ * is simply an overhead and can be avoided.
although one could do drm_memcpy_from_wc(IOSYS_MAP_INIT_VADDR(addr), ...
... Just making you don't take that as a suggestion, I was just thinking
out loud. And as is, it doesn't work as the function expects a
iosys_map *
Lucas De Marhci
