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drm/fb-helper: Clip damage area horizontally

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Clip the damage area horizontally if only a single scanline has been
changed. This is helpful to reduce the memcpy overhead for small writes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220209161617.3553-6-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2022-02-09 17:16:17 +01:00
parent fe23b56f56
commit ded74cafee
1 changed files with 12 additions and 0 deletions
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12
drivers/gpu/drm/drm_fb_helper.c
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@ -690,6 +690,18 @@ static void drm_fb_helper_memory_range_to_clip(struct fb_info *info, off_t off,
u32 x2 = info->var.xres;
u32 y2 = DIV_ROUND_UP(end, info->fix.line_length);
if ((y2 - y1) == 1) {
/*
* We've only written to a single scanline. Try to reduce
* the number of horizontal pixels that need an update.
*/
off_t bit_off = (off % info->fix.line_length) * 8;
off_t bit_end = (end % info->fix.line_length) * 8;
x1 = bit_off / info->var.bits_per_pixel;
x2 = DIV_ROUND_UP(bit_end, info->var.bits_per_pixel);
}
drm_rect_init(clip, x1, y1, x2 - x1, y2 - y1);
}