MIPS: BCM47XX: do not use cpu_wait instruction on BCM4706

The BCM4706 has a problem with the CPU wait instruction. When r4k_wait
or r4k_wait_irqoff is used will just hang and not return from a
msleep(). Removing the cpu_wait functionality is a workaround for this
problem. The BCM4716 does not have this problem.

The BCM4706 SoC uses a MIPS 74K V4.9 CPU.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6288/

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/mips/bcm47xx/setup.c b/arch/mips/bcm47xx/setup.c
index 71e5c7cae814..aa2d8e39a9b0 100644
--- a/arch/mips/bcm47xx/setup.c
+++ b/arch/mips/bcm47xx/setup.c
@@ -32,6 +32,7 @@
 #include <linux/ssb/ssb_embedded.h>
 #include <linux/bcma/bcma_soc.h>
 #include <asm/bootinfo.h>
+#include <asm/idle.h>
 #include <asm/prom.h>
 #include <asm/reboot.h>
 #include <asm/time.h>
@@ -199,6 +200,15 @@ static void __init bcm47xx_register_bcma(void)
                 panic("Failed to initialize BCMA bus (err %d)", err);
 
         bcm47xx_fill_bcma_boardinfo(&bcm47xx_bus.bcma.bus.boardinfo, NULL);
+
+        /* The BCM4706 has a problem with the CPU wait instruction.
+         * When r4k_wait or r4k_wait_irqoff is used will just hang and
+         * not return from a msleep(). Removing the cpu_wait
+         * functionality is a workaround for this problem. The BCM4716
+         * does not have this problem.
+         */
+        if (bcm47xx_bus.bcma.bus.chipinfo.id == BCMA_CHIP_ID_BCM4706)
+                cpu_wait = NULL;
 }
 #endif