Modern processors may need to drain the WB before WFI (8553cb67) · Commits · 戴 / test

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>

arch/arm/mm/proc-v6.S

+2 −0

Original line number	Diff line number	Diff line
		@@ -71,6 +71,8 @@ ENTRY(cpu_v6_reset)
		* 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

arch/arm/mm/proc-v7.S

+1 −0

Original line number	Diff line number	Diff line
		@@ -63,6 +63,7 @@ ENDPROC(cpu_v7_reset)
		* 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)

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