ARM: pm: avoid writing the auxillary control register for ARMv7

For ARMv7 kernels running in the non-secure world, writing to the
auxillary control register causes an abort, so we must avoid directly
writing the auxillary control register.  If the ACR has already been
reinitialized by SoC code, don't try to restore it.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index a773f4e2869c..9049c0764db2 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -248,7 +248,9 @@ ENTRY(cpu_v7_do_resume)
         mcr     p15, 0, r7, c2, c0, 0   @ TTB 0
         mcr     p15, 0, r8, c2, c0, 1   @ TTB 1
         mcr     p15, 0, ip, c2, c0, 2   @ TTB control register
-        mcr     p15, 0, r10, c1, c0, 1  @ Auxiliary control register
+        mrc     p15, 0, r4, c1, c0, 1   @ Read Auxiliary control register
+        teq     r4, r10                 @ Is it already set?
+        mcrne   p15, 0, r10, c1, c0, 1  @ No, so write it
         mcr     p15, 0, r11, c1, c0, 2  @ Co-processor access control
         ldr     r4, =PRRR               @ PRRR
         ldr     r5, =NMRR               @ NMRR