diff --git a/docs/gallium/screen.rst b/docs/gallium/screen.rst
index c2a2a7b1d5f..951b05898fc 100644
--- a/docs/gallium/screen.rst
+++ b/docs/gallium/screen.rst
@@ -606,7 +606,7 @@ The integer capabilities:
     that back-facing primitives should use the back-side color as the FS input
     color.  If unset, mesa/st will lower it to gl_FrontFacing reads in the
     fragment shader.
-* ``PIPE_CAP_CLIP_PLANES``: Driver supports user-defined clip-planes. 0 denotes none, 1 denotes MAX_CLIP_PLANES. > 1 overrides MAX.
+* ``PIPE_CAP_CLIP_PLANES``: Driver supports user-defined clip-planes. 0 denotes none, 1 denotes MAX_CLIP_PLANES. > 1 overrides MAX. When is 0, pipe_rasterizer_state::clip_plane_enable is unused.
 * ``PIPE_CAP_MAX_VERTEX_BUFFERS``: Number of supported vertex buffers.
 * ``PIPE_CAP_OPENCL_INTEGER_FUNCTIONS``: Driver supports extended OpenCL-style integer functions.  This includes average, saturating addition, saturating subtraction, absolute difference, count leading zeros, and count trailing zeros.
 * ``PIPE_CAP_INTEGER_MULTIPLY_32X16``: Driver supports integer multiplication between a 32-bit integer and a 16-bit integer.  If the second operand is 32-bits, the upper 16-bits are ignored, and the low 16-bits are possibly sign extended as necessary.