r300g: Prevent multiple-use textures from getting incorrectly approved.

src/gallium/drivers/r300/r300_screen.c

@@ -182,16 +182,19 @@ static float r300_get_paramf(struct pipe_screen* pscreen, int param)
 static boolean check_tex_2d_format(enum pipe_format format, uint32_t usage,
                                    boolean is_r500)
 {
+    uint32_t retval = 0;
+
     switch (format) {
         /* Supported formats. */
         /* Colorbuffer */
         case PIPE_FORMAT_A4R4G4B4_UNORM:
         case PIPE_FORMAT_R5G6B5_UNORM:
         case PIPE_FORMAT_A1R5G5B5_UNORM:
-            return usage &
+            retval = usage &
                 (PIPE_TEXTURE_USAGE_RENDER_TARGET |
                  PIPE_TEXTURE_USAGE_DISPLAY_TARGET |
                  PIPE_TEXTURE_USAGE_PRIMARY);
+            break;
 
         /* Texture */
         case PIPE_FORMAT_A8R8G8B8_SRGB:
@@ -201,7 +204,8 @@ static boolean check_tex_2d_format(enum pipe_format format, uint32_t usage,
         case PIPE_FORMAT_DXT3_RGBA:
         case PIPE_FORMAT_DXT5_RGBA:
         case PIPE_FORMAT_YCBCR:
-            return usage & PIPE_TEXTURE_USAGE_SAMPLER;
+            retval = usage & PIPE_TEXTURE_USAGE_SAMPLER;
+            break;
 
         /* Colorbuffer or texture */
         case PIPE_FORMAT_A8R8G8B8_UNORM:
@@ -209,19 +213,21 @@ static boolean check_tex_2d_format(enum pipe_format format, uint32_t usage,
         case PIPE_FORMAT_R8G8B8A8_UNORM:
         case PIPE_FORMAT_R8G8B8X8_UNORM:
         case PIPE_FORMAT_I8_UNORM:
-            return usage &
+            retval = usage &
                 (PIPE_TEXTURE_USAGE_RENDER_TARGET |
                  PIPE_TEXTURE_USAGE_DISPLAY_TARGET |
                  PIPE_TEXTURE_USAGE_PRIMARY |
                  PIPE_TEXTURE_USAGE_SAMPLER);
+            break;
 
         /* Z buffer or texture */
         case PIPE_FORMAT_Z16_UNORM:
         /* Z buffer with stencil or texture */
         case PIPE_FORMAT_Z24S8_UNORM:
-            return usage &
+            retval = usage &
                 (PIPE_TEXTURE_USAGE_DEPTH_STENCIL |
                  PIPE_TEXTURE_USAGE_SAMPLER);
+            break;
 
         /* Definitely unsupported formats. */
         /* Non-usable Z buffer/stencil formats. */
@@ -259,7 +265,13 @@ static boolean check_tex_2d_format(enum pipe_format format, uint32_t usage,
             break;
     }
 
-    return FALSE;
+    /* If usage was a mask that contained multiple bits, and not all of them
+     * are supported, this will catch that and return FALSE.
+     * e.g. usage = 2 | 4; retval = 4; (retval >= usage) == FALSE
+     *
+     * This also returns FALSE for any unknown formats.
+     */
+    return (retval >= usage);
 }
 
 /* XXX moar targets */