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fbdev: Fix sys_imageblit() for arbitrary image widths

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Commit 6f29e04938 ("fbdev: Improve performance of sys_imageblit()")
broke sys_imageblit() for image width that are not aligned to 8-bit
boundaries. Fix this by handling the trailing pixels on each line
separately. The performance improvements in the original commit do not
regress by this change.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 6f29e04938 ("fbdev: Improve performance of sys_imageblit()")
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220313192952.12058-2-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2022-03-13 20:29:51 +01:00
parent 5d5fb74630
commit 61bfcb6a3b
1 changed files with 25 additions and 4 deletions
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29
drivers/video/fbdev/core/sysimgblt.c
View file

@ -188,7 +188,7 @@ static void fast_imageblit(const struct fb_image *image, struct fb_info *p,
{
u32 fgx = fgcolor, bgx = bgcolor, bpp = p->var.bits_per_pixel;
u32 ppw = 32/bpp, spitch = (image->width + 7)/8;
u32 bit_mask, eorx;
u32 bit_mask, eorx, shift;
const char *s = image->data, *src;
u32 *dst;
const u32 *tab;
@ -229,17 +229,23 @@ static void fast_imageblit(const struct fb_image *image, struct fb_info *p,
for (i = image->height; i--; ) {
dst = dst1;
shift = 8;
src = s;
/*
* Manually unroll the per-line copying loop for better
* performance. This works until we processed the last
* completely filled source byte (inclusive).
*/
switch (ppw) {
case 4: /* 8 bpp */
for (j = k; j; j -= 2, ++src) {
for (j = k; j >= 2; j -= 2, ++src) {
*dst++ = colortab[(*src >> 4) & bit_mask];
*dst++ = colortab[(*src >> 0) & bit_mask];
}
break;
case 2: /* 16 bpp */
for (j = k; j; j -= 4, ++src) {
for (j = k; j >= 4; j -= 4, ++src) {
*dst++ = colortab[(*src >> 6) & bit_mask];
*dst++ = colortab[(*src >> 4) & bit_mask];
*dst++ = colortab[(*src >> 2) & bit_mask];
@ -247,7 +253,7 @@ static void fast_imageblit(const struct fb_image *image, struct fb_info *p,
}
break;
case 1: /* 32 bpp */
for (j = k; j; j -= 8, ++src) {
for (j = k; j >= 8; j -= 8, ++src) {
*dst++ = colortab[(*src >> 7) & bit_mask];
*dst++ = colortab[(*src >> 6) & bit_mask];
*dst++ = colortab[(*src >> 5) & bit_mask];
@ -259,6 +265,21 @@ static void fast_imageblit(const struct fb_image *image, struct fb_info *p,
}
break;
}
/*
* For image widths that are not a multiple of 8, there
* are trailing pixels left on the current line. Print
* them as well.
*/
for (; j--; ) {
shift -= ppw;
*dst++ = colortab[(*src >> shift) & bit_mask];
if (!shift) {
shift = 8;
++src;
}
}
dst1 += p->fix.line_length;
s += spitch;
}