[igt-dev] [PATCH i-g-t v2 04/13] igt: fb: Move i915 YUV buffer clearing code to a function

[Ville Syrjälä]

On Mon, Jan 14, 2019 at 04:13:02PM +0100, Paul Kocialkowski wrote:
> Hi,
> 
> On Thu, 2019-01-10 at 16:38 +0200, Ville Syrjälä wrote:
> > On Thu, Jan 10, 2019 at 11:10:09AM +0100, Paul Kocialkowski wrote:
> > > On Tue, 2019-01-08 at 16:19 +0100, Maxime Ripard wrote:
> > > > The YUV buffer allocation path for the i915 driver also has some code to
> > > > clear a YUV buffer.
> > > > 
> > > > As that is going to be useful for all the other drivers, let's move it to
> > > > a separate function.
> > > > 
> > > > Signed-off-by: Maxime Ripard <maxime.ripard at bootlin.com>
> > > 
> > > I'm not really sure why clearing the buffers is a useful thing to do
> > > and why we should only do it for YUV and not RGB formats.
> > 
> > 0 = black for RGB, 0 != black for YUV. The memset was just to make
> > things more consistent. But not sure if any test would actually
> > fail if we just drop the memset.
> 
> Right, I understand that this is required for setting the framebuffer
> to black, but I'm just wondering why this has to be done in the first
> place.
> 
> As far as I know, (RGB) buffers allocated with GEM are not zero-ed by
> the allocator,

They are zeroed. You wouldn't want the kernel to leak random
memory contents all over.

> nor by any component in IGT. So I'm wondering why we're
> taking the extra time for clearing buffers in the YUV case.
> 
> Cheers,
> 
> Paul
> 
> > > Anyway, since this code was already there and the refactoring
> > > definitely makes sense:
> > > 
> > > Reviewed-by: Paul Kocialkowski <paul.kocialkowski at bootlin.com>
> > > 
> > > Cheers,
> > > 
> > > Paul
> > > 
> > > > ---
> > > >  lib/igt_fb.c | 80 +++++++++++++++++++++++++++-------------------------
> > > >  1 file changed, 42 insertions(+), 38 deletions(-)
> > > > 
> > > > diff --git a/lib/igt_fb.c b/lib/igt_fb.c
> > > > index 45691fd441d9..d69c3fb2d38d 100644
> > > > --- a/lib/igt_fb.c
> > > > +++ b/lib/igt_fb.c
> > > > @@ -484,6 +484,47 @@ uint64_t igt_fb_tiling_to_mod(uint64_t tiling)
> > > >  	}
> > > >  }
> > > >  
> > > > +static void clear_yuv_buffer(struct igt_fb *fb)
> > > > +{
> > > > +	bool full_range = fb->color_range == IGT_COLOR_YCBCR_FULL_RANGE;
> > > > +	void *ptr;
> > > > +
> > > > +	igt_assert(igt_format_is_yuv(fb->drm_format));
> > > > +
> > > > +	/* Ensure the framebuffer is preallocated */
> > > > +	ptr = igt_fb_map_buffer(fb->fd, fb);
> > > > +	igt_assert(*(uint32_t *)ptr == 0);
> > > > +
> > > > +	switch (fb->drm_format) {
> > > > +	case DRM_FORMAT_NV12:
> > > > +		memset(ptr + fb->offsets[0],
> > > > +		       full_range ? 0x00 : 0x10,
> > > > +		       fb->strides[0] * fb->plane_height[0]);
> > > > +		memset(ptr + fb->offsets[1],
> > > > +		       0x80,
> > > > +		       fb->strides[1] * fb->plane_height[1]);
> > > > +		break;
> > > > +	case DRM_FORMAT_XYUV8888:
> > > > +		wmemset(ptr + fb->offsets[0], full_range ? 0x00008080 : 0x00108080,
> > > > +			fb->strides[0] * fb->plane_height[0] / sizeof(wchar_t));
> > > > +		break;
> > > > +	case DRM_FORMAT_YUYV:
> > > > +	case DRM_FORMAT_YVYU:
> > > > +		wmemset(ptr + fb->offsets[0],
> > > > +			full_range ? 0x80008000 : 0x80108010,
> > > > +			fb->strides[0] * fb->plane_height[0] / sizeof(wchar_t));
> > > > +		break;
> > > > +	case DRM_FORMAT_UYVY:
> > > > +	case DRM_FORMAT_VYUY:
> > > > +		wmemset(ptr + fb->offsets[0],
> > > > +			full_range ? 0x00800080 : 0x10801080,
> > > > +			fb->strides[0] * fb->plane_height[0] / sizeof(wchar_t));
> > > > +		break;
> > > > +	}
> > > > +
> > > > +	igt_fb_unmap_buffer(fb, ptr);
> > > > +}
> > > > +
> > > >  /* helpers to create nice-looking framebuffers */
> > > >  static int create_bo_for_fb(struct igt_fb *fb)
> > > >  {
> > > > @@ -501,50 +542,13 @@ static int create_bo_for_fb(struct igt_fb *fb)
> > > >  		fb->is_dumb = false;
> > > >  
> > > >  		if (is_i915_device(fd)) {
> > > > -			void *ptr;
> > > > -			bool full_range = fb->color_range == IGT_COLOR_YCBCR_FULL_RANGE;
> > > >  
> > > >  			fb->gem_handle = gem_create(fd, fb->size);
> > > >  
> > > >  			gem_set_tiling(fd, fb->gem_handle,
> > > >  				       igt_fb_mod_to_tiling(fb->tiling),
> > > >  				       fb->strides[0]);
> > > > -
> > > > -			gem_set_domain(fd, fb->gem_handle,
> > > > -				       I915_GEM_DOMAIN_GTT, I915_GEM_DOMAIN_GTT);
> > > > -
> > > > -			/* Ensure the framebuffer is preallocated */
> > > > -			ptr = gem_mmap__gtt(fd, fb->gem_handle,
> > > > -					    fb->size, PROT_READ | PROT_WRITE);
> > > > -			igt_assert(*(uint32_t *)ptr == 0);
> > > > -
> > > > -			switch (fb->drm_format) {
> > > > -			case DRM_FORMAT_NV12:
> > > > -				memset(ptr + fb->offsets[0],
> > > > -				       full_range ? 0x00 : 0x10,
> > > > -				       fb->strides[0] * fb->plane_height[0]);
> > > > -				memset(ptr + fb->offsets[1],
> > > > -				       0x80,
> > > > -				       fb->strides[1] * fb->plane_height[1]);
> > > > -				break;
> > > > -			case DRM_FORMAT_XYUV8888:
> > > > -				wmemset(ptr + fb->offsets[0], full_range ? 0x00008080 : 0x00108080,
> > > > -					fb->strides[0] * fb->plane_height[0] / sizeof(wchar_t));
> > > > -				break;
> > > > -			case DRM_FORMAT_YUYV:
> > > > -			case DRM_FORMAT_YVYU:
> > > > -				wmemset(ptr + fb->offsets[0],
> > > > -					full_range ? 0x80008000 : 0x80108010,
> > > > -					fb->strides[0] * fb->plane_height[0] / sizeof(wchar_t));
> > > > -				break;
> > > > -			case DRM_FORMAT_UYVY:
> > > > -			case DRM_FORMAT_VYUY:
> > > > -				wmemset(ptr + fb->offsets[0],
> > > > -					full_range ? 0x00800080 : 0x10801080,
> > > > -					fb->strides[0] * fb->plane_height[0] / sizeof(wchar_t));
> > > > -				break;
> > > > -			}
> > > > -			gem_munmap(ptr, fb->size);
> > > > +			clear_yuv_buffer(fd);
> > > >  
> > > >  			return fb->gem_handle;
> > > >  		} else {
> > > -- 
> > > Paul Kocialkowski, Bootlin
> > > Embedded Linux and kernel engineering
> > > https://bootlin.com
> -- 
> Paul Kocialkowski, Bootlin
> Embedded Linux and kernel engineering
> https://bootlin.com

-- 
Ville Syrjälä
Intel