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authorThomas Zimmermann <tzimmermann@suse.de>2022-02-23 22:38:03 +0300
committerThomas Zimmermann <tzimmermann@suse.de>2022-03-02 22:22:33 +0300
commit0d03011894d23241db1a1cad5c12aede60897d5e (patch)
tree5730baad2f6dd3c954e923837ffe731f6135f3ba
parent3c54c95bd917d43d12fe1b192df9aa4c5973449b (diff)
downloadlinux-0d03011894d23241db1a1cad5c12aede60897d5e.tar.xz
fbdev: Improve performance of cfb_imageblit()
Improve the performance of cfb_imageblit() by manually unrolling the inner blitting loop and moving some invariants out. The compiler failed to do this automatically. This change keeps cfb_imageblit() in sync with sys_imagebit(). A microbenchmark measures the average number of CPU cycles for cfb_imageblit() after a stabilizing period of a few minutes (i7-4790, FullHD, simpledrm, kernel with debugging). cfb_imageblit(), new: 15724 cycles cfb_imageblit(): old: 30566 cycles In the optimized case, cfb_imageblit() is now ~2x faster than before. v3: * fix commit description (Pekka) Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Acked-by: Sam Ravnborg <sam@ravnborg.org> Link: https://patchwork.freedesktop.org/patch/msgid/20220223193804.18636-5-tzimmermann@suse.de
-rw-r--r--drivers/video/fbdev/core/cfbimgblt.c51
1 files changed, 42 insertions, 9 deletions
diff --git a/drivers/video/fbdev/core/cfbimgblt.c b/drivers/video/fbdev/core/cfbimgblt.c
index 01b01a279681..7361cfabdd85 100644
--- a/drivers/video/fbdev/core/cfbimgblt.c
+++ b/drivers/video/fbdev/core/cfbimgblt.c
@@ -218,23 +218,29 @@ static inline void fast_imageblit(const struct fb_image *image, struct fb_info *
{
u32 fgx = fgcolor, bgx = bgcolor, bpp = p->var.bits_per_pixel;
u32 ppw = 32/bpp, spitch = (image->width + 7)/8;
- u32 bit_mask, end_mask, eorx, shift;
+ u32 bit_mask, eorx;
const char *s = image->data, *src;
u32 __iomem *dst;
const u32 *tab = NULL;
+ size_t tablen;
+ u32 colortab[16];
int i, j, k;
switch (bpp) {
case 8:
tab = fb_be_math(p) ? cfb_tab8_be : cfb_tab8_le;
+ tablen = 16;
break;
case 16:
tab = fb_be_math(p) ? cfb_tab16_be : cfb_tab16_le;
+ tablen = 4;
break;
case 32:
- default:
tab = cfb_tab32;
+ tablen = 2;
break;
+ default:
+ return;
}
for (i = ppw-1; i--; ) {
@@ -248,15 +254,42 @@ static inline void fast_imageblit(const struct fb_image *image, struct fb_info *
eorx = fgx ^ bgx;
k = image->width/ppw;
- for (i = image->height; i--; ) {
- dst = (u32 __iomem *) dst1, shift = 8; src = s;
+ for (i = 0; i < tablen; ++i)
+ colortab[i] = (tab[i] & eorx) ^ bgx;
- for (j = k; j--; ) {
- shift -= ppw;
- end_mask = tab[(*src >> shift) & bit_mask];
- FB_WRITEL((end_mask & eorx)^bgx, dst++);
- if (!shift) { shift = 8; src++; }
+ for (i = image->height; i--; ) {
+ dst = (u32 __iomem *)dst1;
+ src = s;
+
+ switch (ppw) {
+ case 4: /* 8 bpp */
+ for (j = k; j; j -= 2, ++src) {
+ FB_WRITEL(colortab[(*src >> 4) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 0) & bit_mask], dst++);
+ }
+ break;
+ case 2: /* 16 bpp */
+ for (j = k; j; j -= 4, ++src) {
+ FB_WRITEL(colortab[(*src >> 6) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 4) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 2) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 0) & bit_mask], dst++);
+ }
+ break;
+ case 1: /* 32 bpp */
+ for (j = k; j; j -= 8, ++src) {
+ FB_WRITEL(colortab[(*src >> 7) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 6) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 5) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 4) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 3) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 2) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 1) & bit_mask], dst++);
+ FB_WRITEL(colortab[(*src >> 0) & bit_mask], dst++);
+ }
+ break;
}
+
dst1 += p->fix.line_length;
s += spitch;
}