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Commit 9a956b15 authored by Chris Wilson's avatar Chris Wilson Committed by Daniel Vetter
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drm: Optimise power-of-two alignments in drm_mm_scan_add_block() 



For power-of-two alignments, we can avoid the 64bit divide and do a
simple bitwise add instead.

v2: s/alignment_mask/remainder_mask/

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161222083641.2691-32-chris@chris-wilson.co.uk
parent 0b04d474

drivers/gpu/drm/drm_mm.c

+8 −1
Original line number Diff line number Diff line
@@ -742,8 +742,12 @@ void drm_mm_scan_init_with_range(struct drm_mm_scan *scan, 


	scan->mm = mm;



	if (alignment <= 1)

		alignment = 0;



	scan->color = color;

	scan->alignment = alignment;

	scan->remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;

	scan->size = size;

	scan->flags = flags;
@@ -811,6 +815,9 @@ bool drm_mm_scan_add_block(struct drm_mm_scan *scan, 
	if (scan->alignment) {

		u64 rem;



		if (likely(scan->remainder_mask))

			rem = adj_start & scan->remainder_mask;

		else

			div64_u64_rem(adj_start, scan->alignment, &rem);

		if (rem) {

			adj_start -= rem;

include/drm/drm_mm.h

+1 −0
Original line number Diff line number Diff line
@@ -110,6 +110,7 @@ struct drm_mm_scan { 


	u64 size;

	u64 alignment;

	u64 remainder_mask;



	u64 range_start;

	u64 range_end;