From c2b706f8afed02f15ef6fd067e47d60e1f0987a5 Mon Sep 17 00:00:00 2001 From: Chad Versace Date: Fri, 10 Mar 2017 15:13:16 -0800 Subject: [PATCH] isl: Drop misplaced comment about padding isl has a giant comment that explains the hardware's padding requirements. (Hint: Cache lines and page faults). But the comment is in the wrong place, in isl_calc_linear_row_pitch(), which is unrelated to padding. The important parts of that comment were copied to isl_apply_surface_padding() long ago. So drop the misplaced comment. Reviewed-by: Nanley Chery Reviewed-by: Jason Ekstrand --- src/intel/isl/isl.c | 46 --------------------------------------------- 1 file changed, 46 deletions(-) diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c index b4bdf2059ac..515d2c3fa31 100644 --- a/src/intel/isl/isl.c +++ b/src/intel/isl/isl.c @@ -1004,53 +1004,7 @@ isl_calc_linear_row_pitch(const struct isl_device *dev, const struct isl_extent2d *phys_slice0_sa) { const struct isl_format_layout *fmtl = isl_format_get_layout(info->format); - uint32_t row_pitch = info->min_pitch; - - /* First, align the surface to a cache line boundary, as the PRM explains - * below. - * - * From the Broadwell PRM >> Volume 5: Memory Views >> Common Surface - * Formats >> Surface Padding Requirements >> Render Target and Media - * Surfaces: - * - * The data port accesses data (pixels) outside of the surface if they - * are contained in the same cache request as pixels that are within the - * surface. These pixels will not be returned by the requesting message, - * however if these pixels lie outside of defined pages in the GTT, - * a GTT error will result when the cache request is processed. In order - * to avoid these GTT errors, “padding” at the bottom of the surface is - * sometimes necessary. - * - * From the Broadwell PRM >> Volume 5: Memory Views >> Common Surface - * Formats >> Surface Padding Requirements >> Sampling Engine Surfaces: - * - * The sampling engine accesses texels outside of the surface if they - * are contained in the same cache line as texels that are within the - * surface. These texels will not participate in any calculation - * performed by the sampling engine and will not affect the result of - * any sampling engine operation, however if these texels lie outside of - * defined pages in the GTT, a GTT error will result when the cache line - * is accessed. In order to avoid these GTT errors, “padding” at the - * bottom and right side of a sampling engine surface is sometimes - * necessary. - * - * It is possible that a cache line will straddle a page boundary if the - * base address or pitch is not aligned. All pages included in the cache - * lines that are part of the surface must map to valid GTT entries to - * avoid errors. To determine the necessary padding on the bottom and - * right side of the surface, refer to the table in Alignment Unit Size - * section for the i and j parameters for the surface format in use. The - * surface must then be extended to the next multiple of the alignment - * unit size in each dimension, and all texels contained in this - * extended surface must have valid GTT entries. - * - * For example, suppose the surface size is 15 texels by 10 texels and - * the alignment parameters are i=4 and j=2. In this case, the extended - * surface would be 16 by 10. Note that these calculations are done in - * texels, and must be converted to bytes based on the surface format - * being used to determine whether additional pages need to be defined. - */ assert(phys_slice0_sa->w % fmtl->bw == 0); const uint32_t bs = fmtl->bpb / 8; row_pitch = MAX(row_pitch, bs * (phys_slice0_sa->w / fmtl->bw)); -- 2.30.2