The logic was reversed from what the hw actually exposed.
Fixes graphics corruption in certain harvest configurations.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
 
        if ((rdev->config.cayman.max_backends_per_se == 1) &&
            (rdev->flags & RADEON_IS_IGP)) {
-               if ((disabled_rb_mask & 3) == 1) {
-                       /* RB0 disabled, RB1 enabled */
-                       tmp = 0x11111111;
-               } else {
+               if ((disabled_rb_mask & 3) == 2) {
                        /* RB1 disabled, RB0 enabled */
                        tmp = 0x00000000;
+               } else {
+                       /* RB0 disabled, RB1 enabled */
+                       tmp = 0x11111111;
                }
        } else {
                tmp = gb_addr_config & NUM_PIPES_MASK;