isl/docs/tiling: Add Tile4 docs

Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12550>
This commit is contained in:
Jason Ekstrand 2021-07-01 14:06:34 -05:00 committed by Marge Bot
parent cfb0d931f2
commit 3c3b75a2b7

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@ -246,6 +246,36 @@ ISL, we represent a W-tile as a tiling with a logical dimension of 64el x 64el
but a physical size of 128B x 32rows. This cleanly takes care of the pitch
issue above and seems to nicely model the hardware.
Tile4
-----
The tile4 format, introduced on Xe-HP, is somewhat similar to Y but with more
internal shuffling. Each tile4 tile is an 8x8 grid of cache lines arranged
as follows:
===== ===== ===== ===== ===== ===== ===== =====
===== ===== ===== ===== ===== ===== ===== =====
0x000 0x040 0x080 0x0a0 0x200 0x240 0x280 0x2a0
0x100 0x140 0x180 0x1a0 0x300 0x340 0x380 0x3a0
0x400 0x440 0x480 0x4a0 0x600 0x640 0x680 0x6a0
0x500 0x540 0x580 0x5a0 0x700 0x740 0x780 0x7a0
0x800 0x840 0x880 0x8a0 0xa00 0xa40 0xa80 0xaa0
0x900 0x940 0x980 0x9a0 0xb00 0xb40 0xb80 0xba0
0xc00 0xc40 0xc80 0xca0 0xe00 0xe40 0xe80 0xea0
0xd00 0xd40 0xd80 0xda0 0xf00 0xf40 0xf80 0xfa0
===== ===== ===== ===== ===== ===== ===== =====
Each 64B cache line within the tile is laid out the same way as for a Y-tile,
as 4 rows of 16B each:
==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ====
==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ====
0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a 0x0b 0x0c 0x0d 0x0e 0x0f
0x10 0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1a 0x1b 0x1c 0x1d 0x1e 0x1f
0x20 0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 0x29 0x2a 0x2b 0x2c 0x2d 0x2e 0x2f
0x30 0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x39 0x3a 0x3b 0x3c 0x3d 0x3e 0x3f
==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== ====
Tiling as a bit pattern
-----------------------
@ -281,6 +311,7 @@ the tile are given by the table below:
:cpp:enumerator:`isl_tiling::ISL_TILING_X` :math:`v_2` :math:`v_1` :math:`v_0` :math:`u_8` :math:`u_7` :math:`u_6` :math:`u_5` :math:`u_4` :math:`u_3` :math:`u_2` :math:`u_1` :math:`u_0`
:cpp:enumerator:`isl_tiling::ISL_TILING_Y0` :math:`u_6` :math:`u_5` :math:`u_4` :math:`v_4` :math:`v_3` :math:`v_2` :math:`v_1` :math:`v_0` :math:`u_3` :math:`u_2` :math:`u_1` :math:`u_0`
:cpp:enumerator:`isl_tiling::ISL_TILING_W` :math:`u_5` :math:`u_4` :math:`u_3` :math:`v_5` :math:`v_4` :math:`v_3` :math:`v_2` :math:`u_2` :math:`v_1` :math:`u_1` :math:`v_0` :math:`u_0`
:cpp:enumerator:`isl_tiling::ISL_TILING_4` :math:`v_4` :math:`v_3` :math:`u_6` :math:`v_2` :math:`u_5` :math:`u_4` :math:`v_1` :math:`v_0` :math:`u_3` :math:`u_2` :math:`u_1` :math:`u_0`
=========================================== =========== =========== =========== =========== =========== =========== =========== =========== =========== =========== =========== ===========
Constructing the mapping this way makes a lot of sense when you think about