MIPS: Alchemy: Default to noncoherent IO on Au1200 AB

CONFIG_DMA_COHERENT is no longer set; default to noncoherent io on
Au1200 revision AB to make USB work.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/6745/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/alchemy/common/setup.c b/arch/mips/alchemy/common/setup.c
index 566a1743..8267e3c 100644
--- a/arch/mips/alchemy/common/setup.c
+++ b/arch/mips/alchemy/common/setup.c
@@ -67,6 +67,12 @@
 	case ALCHEMY_CPU_AU1500:
 	case ALCHEMY_CPU_AU1100:
 		coherentio = 0;
+		break;
+	case ALCHEMY_CPU_AU1200:
+		/* Au1200 AB USB does not support coherent memory */
+		if (0 == (read_c0_prid() & PRID_REV_MASK))
+			coherentio = 0;
+		break;
 	}
 
 	board_setup();	/* board specific setup */