Mostly LGTM, here are a few nits. On Wed, 2019-06-12 at 23:17 -0300, Brian Starkey wrote: > To use writeback buffers as a CRC source, we need to be able to hash > them. Implement a simple FVA-1a hashing routine for this purpose. > > Doing a bytewise hash on the framebuffer directly can be very slow if > the memory is noncached. By making a copy of each line in the FB first > (which can take advantage of word-access speedup), we can do the hash > on a cached copy, which is much faster (10x speedup on my platform). > > v6: use igt_memcpy_from_wc() instead of plain memcpy, as suggested by > Chris Wilson > > Signed-off-by: Brian Starkey <brian.starkey@xxxxxxx> > [rebased and updated to the most recent API] > Signed-off-by: Liviu Dudau <liviu.dudau@xxxxxxx> > --- > lib/igt_fb.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > lib/igt_fb.h | 3 +++ > 2 files changed, 69 insertions(+) > > diff --git a/lib/igt_fb.c b/lib/igt_fb.c > index 9d4f905e..d07dae39 100644 > --- a/lib/igt_fb.c > +++ b/lib/igt_fb.c > @@ -3256,6 +3256,72 @@ bool igt_fb_supported_format(uint32_t drm_format) > return false; > } > > +/* > + * This implements the FNV-1a hashing algorithm instead of CRC, for > + * simplicity > + * http://www.isthe.com/chongo/tech/comp/fnv/index.html > + * > + * hash = offset_basis > + * for each octet_of_data to be hashed > + * hash = hash xor octet_of_data > + * hash = hash * FNV_prime > + * return hash > + * > + * 32 bit offset_basis = 2166136261 > + * 32 bit FNV_prime = 224 + 28 + 0x93 = 16777619 > + */ > +int igt_fb_get_crc(struct igt_fb *fb, igt_crc_t *crc) > +{ > +#define FNV1a_OFFSET_BIAS 2166136261 > +#define FNV1a_PRIME 16777619 I'd just use plain uint32_t variables for those, but no big deal. > + uint32_t hash; > + void *map; > + char *ptr, *line = NULL; > + int x, y, cpp = igt_drm_format_to_bpp(fb->drm_format) / 8; > + uint32_t stride = calc_plane_stride(fb, 0); We could return -EINVAL in case fb->num_planes != 1. > + if (fb->is_dumb) > + map = kmstest_dumb_map_buffer(fb->fd, fb->gem_handle, fb->size, > + PROT_READ); > + else > + map = gem_mmap__gtt(fb->fd, fb->gem_handle, fb->size, > + PROT_READ); > + ptr = map; Nit: no need for this, can assign the result of mmap directly to ptr. > + > + /* > + * Framebuffers are often uncached, which can make byte-wise accesses > + * very slow. We copy each line of the FB into a local buffer to speed > + * up the hashing. > + */ > + line = malloc(stride); > + if (!line) { > + munmap(map, fb->size); > + return -ENOMEM; > + } > + > + hash = FNV1a_OFFSET_BIAS; > + > + for (y = 0; y < fb->height; y++, ptr += stride) { > + > + igt_memcpy_from_wc(line, ptr, stride); Nit: no need to copy the whole stride actually, we can just copy fb->width * cpp since we're only going to read that. > + > + for (x = 0; x < fb->width * cpp; x++) { > + hash ^= line[x]; > + hash *= FNV1a_PRIME; > + } > + } > + > + crc->n_words = 1; > + crc->crc[0] = hash; > + > + free(line); > + munmap(map, fb->size); > + > + return 0; > +#undef FNV1a_OFFSET_BIAS > +#undef FNV1a_PRIME > +} > + > /** > * igt_format_is_yuv: > * @drm_format: drm fourcc > diff --git a/lib/igt_fb.h b/lib/igt_fb.h > index adefebe1..a2741c05 100644 > --- a/lib/igt_fb.h > +++ b/lib/igt_fb.h > @@ -37,6 +37,7 @@ > #include <i915_drm.h> > > #include "igt_color_encoding.h" > +#include "igt_debugfs.h" > > /* > * Internal format to denote a buffer compatible with pixman's > @@ -194,5 +195,7 @@ int igt_format_plane_bpp(uint32_t drm_format, int plane); > void igt_format_array_fill(uint32_t **formats_array, unsigned int *count, > bool allow_yuv); > > +int igt_fb_get_crc(struct igt_fb *fb, igt_crc_t *crc); > + > #endif /* __IGT_FB_H__ */ > > _______________________________________________ > igt-dev mailing list > igt-dev@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/igt-dev _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
