[Intel-gfx] [PATCH v2 2/7] drm: Add drm_memcpy_from_wc() variant which accepts destination address

[Lucas De Marchi]

On Thu, Mar 03, 2022 at 11:30:08PM +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 at linux.intel.com>
>Cc: Maxime Ripard <mripard at kernel.org>
>Cc: Thomas Zimmermann <tzimmermann at suse.de>
>Cc: David Airlie <airlied at linux.ie>
>Cc: Daniel Vetter <daniel at ffwll.ch>
>Cc: Thomas Hellstr_m <thomas.hellstrom at linux.intel.com>
>Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>
>Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan at intel.com>
>---
> 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..97959eecc300 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

drm_memcpy_from_wc() for kernel doc

>+ * address. Useful in situations where passing destination address as iosys_map
>+ * is simply an overhead and can be avoided.
>+ */
>+void drm_memcpy_from_wc_vaddr(void *dst, const struct iosys_map *src,

As in the first version, still don't like the name, but ok.


Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>


Lucas De Marchi