On Sep 7, 2016 12:23 PM, "Chad Versace" <<a href="mailto:chadversary@chromium.org">chadversary@chromium.org</a>> wrote: > > On Fri 02 Sep 2016, Jason Ekstrand wrote: > > --- > > src/intel/isl/isl.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 58 insertions(+), 2 deletions(-) > > > > diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c > > index 33e83b1..cb9eb23 100644 > > --- a/src/intel/isl/isl.c > > +++ b/src/intel/isl/isl.c > > @@ -1284,6 +1284,63 @@ isl_surf_get_hiz_surf(const struct isl_device *dev, > > assert(surf->msaa_layout == ISL_MSAA_LAYOUT_NONE || > > surf->msaa_layout == ISL_MSAA_LAYOUT_INTERLEAVED); > > > > + /* From the Broadwell PRM Vol. 7, "Hierarchical Depth Buffer": > > + * > > + * "The Surface Type, Height, Width, Depth, Minimum Array Element, Render > > + * Target View Extent, and Depth Coordinate Offset X/Y of the > > + * hierarchical depth buffer are inherited from the depth buffer. The > > + * height and width of the hierarchical depth buffer that must be > > + * allocated are computed by the following formulas, where HZ is the > > + * hierarchical depth buffer and Z is the depth buffer. The Z_Height, > > + * Z_Width, and Z_Depth values given in these formulas are those present > > + * in 3DSTATE_DEPTH_BUFFER incremented by one. > > + * > > + * "The value of Z_Height and Z_Width must each be multiplied by 2 before > > + * being applied to the table below if Number of Multisamples is set to > > + * NUMSAMPLES_4. The value of Z_Height must be multiplied by 2 and > > + * Z_Width must be multiplied by 4 before being applied to the table > > + * below if Number of Multisamples is set to NUMSAMPLES_8." > > + * > > + * In the Sky Lake PRM, the second paragraph is replaced with this: > > + * > > + * "The Z_Height and Z_Width values must equal those present in > > + * 3DSTATE_DEPTH_BUFFER incremented by one." > > + * > > + * In other words, on Sandy Bridge through Broadwell, each 128-bit HiX > > Typo s/HiX/HiZ/ > > > + * block corresponds to a region of 8x4 samples in the primary depth > > + * surface. On Sky Lake, on the other hand, each HiZ block corresponds to > > + * a region of 8x4 pixels in the primary depth surface regarldess of the > > Typo ^^^^^^^^^^ > > > + * number of samples. The dimensions of a HiZ block in both pixes and > > Typo ^^^^^ > > > + * samples are given in the table below: > > + * > > + * | SNB - BDW | SKL+ > > + * ------------------+------------- > > + * 1x | 8 x 4 sa | 8 x 4 sa > > + * MSAA | 8 x 4 px | 8 x 4 px > > + * ------------------+------------- > > + * 2x | 8 x 4 sa | 16 x 4 sa > > + * MSAA | 4 x 4 px | 8 x 4 px > > + * ------------------+------------- > > + * 4x | 8 x 4 sa | 16 x 8 sa > > + * MSAA | 4 x 2 px | 8 x 4 px > > + * ------------------+------------- > > + * 8x | 8 x 4 sa | 32 x 8 sa > > + * MSAA | 2 x 2 px | 8 x 4 px > > + * ------------------+------------- > > + * 16x | N/A | 32 x 16 sa > > + * MSAA | N/A | 8 x 4 px > > + * ------------------+------------- > > THANK YOU THANK YOU THANK YOU. > You win all the cat gifs [<a href="https://s-media-cache-ak0.pinimg.com/originals/34/71/dc/3471dc5d6443b2af5476ad3dbbca9d7c.jpg">https://s-media-cache-ak0.pinimg.com/originals/34/71/dc/3471dc5d6443b2af5476ad3dbbca9d7c.jpg</a>] Yeah... This stuff has proven surprisingly difficult to reason about. The table gives us a central spot to write down "the facts" so that future generations of ISL hackers understand what's going on. > > + * > > + * There are a number of different ways that this discrepency could be > > + * handled. The way we have chosen is to simply make MSAA HiZ have the > > + * same number of samples as the parent surface pre-Sky Lake and always be > > + * single-sampled on Sky Lake and above. Since the block sizes of > > + * compressed formats are given in samples, this neatly handles everything > > + * without the need for additional HiZ formats with different block sizes > > + * on SKL+. > > + */ > > This makes perfect sense. > > > + const unsigned samples = ISL_DEV_GEN(dev) >= 9 ? 1 : surf->samples; > > + > > isl_surf_init(dev, hiz_surf, > > .dim = ISL_SURF_DIM_2D, > > .format = ISL_FORMAT_HIZ, > > @@ -1292,8 +1349,7 @@ isl_surf_get_hiz_surf(const struct isl_device *dev, > > .depth = 1, > > .levels = surf->levels, > > .array_len = surf->logical_level0_px.array_len, > > - /* On SKL+, HiZ is always single-sampled */ > > - .samples = ISL_DEV_GEN(dev) >= 9 ? 1 : surf->samples, > > + .samples = samples, > > .usage = ISL_SURF_USAGE_HIZ_BIT, > > .tiling_flags = ISL_TILING_HIZ_BIT); > > } > > -- > > Reviewed-by: Chad Versace <<a href="mailto:chadversary@chromium.org">chadversary@chromium.org</a>> Thanks. I'll get the convent typos fixed when I get back to my computer. --Jason