Modern processors may need to drain the WB before WFI
Since WFI may cause the processor to enter a low-power mode, data may
still be in the write buffer. This patch adds a DSB (or DWB) to the
cpu_(v6|v7)_do_idle functions before the WFI.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm/mm/proc-v6.S b/arch/arm/mm/proc-v6.S
index 294943b..f0cc599 100644
--- a/arch/arm/mm/proc-v6.S
+++ b/arch/arm/mm/proc-v6.S
@@ -71,6 +71,8 @@
* IRQs are already disabled.
*/
ENTRY(cpu_v6_do_idle)
+ mov r1, #0
+ mcr p15, 0, r1, c7, c10, 4 @ DWB - WFI may enter a low-power mode
mcr p15, 0, r1, c7, c0, 4 @ wait for interrupt
mov pc, lr
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 721b7d5..0e11d97 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -63,6 +63,7 @@
* IRQs are already disabled.
*/
ENTRY(cpu_v7_do_idle)
+ dsb @ WFI may enter a low-power mode
wfi
mov pc, lr
ENDPROC(cpu_v7_do_idle)