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Modern processors may need to drain the WB before WFI

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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>
This commit is contained in:
Catalin Marinas 2008-11-10 14:14:11 +00:00
parent 73b63efaac
commit 8553cb67d2
2 changed files with 3 additions and 0 deletions
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2
arch/arm/mm/proc-v6.S
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@ -71,6 +71,8 @@ ENTRY(cpu_v6_reset)
* IRQs are already disabled. * IRQs are already disabled.
*/ */
ENTRY(cpu_v6_do_idle) 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 mcr p15, 0, r1, c7, c0, 4 @ wait for interrupt
mov pc, lr mov pc, lr

1
arch/arm/mm/proc-v7.S
View File

@ -63,6 +63,7 @@ ENDPROC(cpu_v7_reset)
* IRQs are already disabled. * IRQs are already disabled.
*/ */
ENTRY(cpu_v7_do_idle) ENTRY(cpu_v7_do_idle)
dsb @ WFI may enter a low-power mode
wfi wfi
mov pc, lr mov pc, lr
ENDPROC(cpu_v7_do_idle) ENDPROC(cpu_v7_do_idle)