Commit 0d03011894d2 ("fbdev: Improve performance of cfb_imageblit()")
broke cfb_imageblit() for image widths 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@xxxxxxx>
Fixes: 0d03011894d2 ("fbdev: Improve performance of cfb_imageblit()")
Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
---
drivers/video/fbdev/core/cfbimgblt.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/drivers/video/fbdev/core/cfbimgblt.c b/drivers/video/fbdev/core/cfbimgblt.c
index 7361cfabdd85..9ebda4e0dc7a 100644
--- a/drivers/video/fbdev/core/cfbimgblt.c
+++ b/drivers/video/fbdev/core/cfbimgblt.c
@@ -218,7 +218,7 @@ 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, eorx;
+ u32 bit_mask, eorx, shift;
const char *s = image->data, *src;
u32 __iomem *dst;
const u32 *tab = NULL;
@@ -259,17 +259,23 @@ static inline void fast_imageblit(const struct fb_image *image, struct fb_info *
for (i = image->height; i--; ) {
dst = (u32 __iomem *)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) {
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) {
+ for (j = k; j >= 4; 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++);
@@ -277,7 +283,7 @@ static inline void fast_imageblit(const struct fb_image *image, struct fb_info *
}
break;
case 1: /* 32 bpp */
- for (j = k; j; j -= 8, ++src) {
+ for (j = k; j >= 8; 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++);
@@ -290,6 +296,20 @@ static inline void fast_imageblit(const struct fb_image *image, struct fb_info *
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;
+ FB_WRITEL(colortab[(*src >> shift) & bit_mask], dst++);
+ if (!shift) {
+ shift = 8;
+ ++src;
+ }
+ }
+
dst1 += p->fix.line_length;
s += spitch;
}
--
2.35.1
