Hi Am 08.03.22 um 23:52 schrieb Marek Szyprowski:
Hi Thomas, On 23.02.2022 20:38, Thomas Zimmermann wrote: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@xxxxxxx> Acked-by: Sam Ravnborg <sam@xxxxxxxxxxxx> Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>This patch landed recently in linux next-20220308 as commit 0d03011894d2 ("fbdev: Improve performance of cfb_imageblit()"). Sadly it causes a freeze after DRM and emulated fbdev initialization on various Samsung Exynos ARM 32bit based boards. This happens when kernel is compiled from exynos_defconfig. Surprisingly when kernel is compiled from multi_v7_defconfig all those boards boot fine, so this is a matter of one of the debugging options enabled in the exynos_defconfig. I will try to analyze this further and share the results. Reverting $subject on top of next-20220308 fixes the boot issue.
Thanks for reporting. I don't have the hardware to reproduce it and there's no obvious difference to the original version. It's supposed to be the same algorithm with a different implementation. Unless you can figure out the issue, we can also revert the patch easily.
Best regards Thomas
--- drivers/video/fbdev/core/cfbimgblt.c | 51 +++++++++++++++++++++++----- 1 file 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; }Best regards
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
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