diff options
Diffstat (limited to 'src/intel/isl/isl.c')
| -rw-r--r-- | src/intel/isl/isl.c | 60 |
1 files changed, 58 insertions, 2 deletions
diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c index 9ae2bfefb44..1a57f7c1580 100644 --- a/src/intel/isl/isl.c +++ b/src/intel/isl/isl.c @@ -1315,6 +1315,63 @@ 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 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 regardless of the + * number of samples. The dimensions of a HiZ block in both pixels and + * 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 + * ------+-----------+------------- + * + * 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+. + */ + 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, @@ -1323,8 +1380,7 @@ 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); } |