gallium: add PIPE_CAP_RASTERIZER_SUBPIXEL_BITS

Reviewed-by: Roland Scheidegger <sroland@vmware.com>

src/gallium/auxiliary/util/u_screen.c

@@ -254,6 +254,9 @@ u_pipe_screen_get_param_defaults(struct pipe_screen *pscreen,
    case PIPE_CAP_NATIVE_FENCE_FD:
       return 0;
 
+   case PIPE_CAP_RASTERIZER_SUBPIXEL_BITS:
+      return 4; /* GLES 2.0 minimum value */
+
    case PIPE_CAP_GLSL_OPTIMIZE_CONSERVATIVELY:
       return 1;
 

src/gallium/docs/source/screen.rst

@@ -342,6 +342,8 @@ The integer capabilities:
   for ``pipe_rasterizer_state::offset_units_unscaled``.
 * ``PIPE_CAP_VIEWPORT_SUBPIXEL_BITS``: Number of bits of subpixel precision for
   floating point viewport bounds.
+* ``PIPE_CAP_RASTERIZER_SUBPIXEL_BITS``: Number of bits of subpixel precision used
+  by the rasterizer.
 * ``PIPE_CAP_MIXED_COLOR_DEPTH_BITS``: Whether there is non-fallback
   support for color/depth format combinations that use a different
   number of bits. For the purpose of this cap, Z24 is treated as

src/gallium/drivers/r600/r600_pipe.c

@@ -507,6 +507,7 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_MAX_VIEWPORTS:
 		return R600_MAX_VIEWPORTS;
 	case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
+	case PIPE_CAP_RASTERIZER_SUBPIXEL_BITS:
 		return 8;
 
 	/* Timer queries, present when the clock frequency is non zero. */

src/gallium/drivers/radeonsi/si_get.c

@@ -286,6 +286,7 @@ static int si_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 	case PIPE_CAP_MAX_VIEWPORTS:
 		return SI_MAX_VIEWPORTS;
 	case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
+	case PIPE_CAP_RASTERIZER_SUBPIXEL_BITS:
 	case PIPE_CAP_MAX_RENDER_TARGETS:
 		return 8;
 	case PIPE_CAP_FRAMEBUFFER_MSAA_CONSTRAINTS:

src/gallium/include/pipe/p_defines.h

@@ -774,6 +774,7 @@ enum pipe_cap
    PIPE_CAP_MAX_WINDOW_RECTANGLES,
    PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED,
    PIPE_CAP_VIEWPORT_SUBPIXEL_BITS,
+   PIPE_CAP_RASTERIZER_SUBPIXEL_BITS,
    PIPE_CAP_MIXED_COLOR_DEPTH_BITS,
    PIPE_CAP_TGSI_ARRAY_COMPONENTS,
    PIPE_CAP_STREAM_OUTPUT_INTERLEAVE_BUFFERS,

src/mesa/state_tracker/st_extensions.c

@@ -111,6 +111,7 @@ void st_init_limits(struct pipe_screen *screen,
    c->MaxRenderbufferSize = c->MaxTextureRectSize;
 
    c->SubPixelBits =
+      screen->get_param(screen, PIPE_CAP_RASTERIZER_SUBPIXEL_BITS);
    c->ViewportSubpixelBits =
       screen->get_param(screen, PIPE_CAP_VIEWPORT_SUBPIXEL_BITS);