gallium: add a a new cap for changing the TGSI TG4 instruction encoding

[mesa.git] / src / gallium / docs / source / tgsi.rst

diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index d58b23f024b3998d11476b49d03c8175670bac8b..e053e821ecd54abfea2c7f1d4a14e5dbe01870a2 100644 (file)
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -962,14 +962,22 @@ XXX doesn't look like most of the opcodes really belong here.
   require another CAP is hw can do it natively. For now we lower that before
   TGSI.
 
+  PIPE_CAP_TGSI_TG4_COMPONENT_IN_SWIZZLE changes the encoding so that component
+  is stored in the sampler source swizzle x.
+
 .. math::
 
    coord = src0
 
+   (without TGSI_TG4_COMPONENT_IN_SWIZZLE)
    component = src1
 
    dst = texture\_gather4 (unit, coord, component)
 
+   (with TGSI_TG4_COMPONENT_IN_SWIZZLE)
+   dst = texture\_gather4 (unit, coord)
+   component is encoded in sampler swizzle.
+
 (with SM5 - cube array shadow)
 
 .. math::