[U-Boot] [PATCH] armv7: psci: cpu_off: flush D-Cache before disable D-Cache

[U-Boot] [PATCH] armv7: psci: cpu_off: flush D-Cache before disable D-Cache

[Peng Fan]

Before disable cache, need to first flush cache.

There maybe dirty data in D-Cache before disable D-Cache.
After disable D-Cache, the first store instructions in
psci_v7_flush_dcache_all will directly store registers
{r4-r5, r7, r9-r11, lr} to memory.
If there is dirty data before disable D-Cache,
psci_v7_flush_dcache_all will flush data to memory,
and may overwrite the memory that hold the registers
{r4-r5, r7, r9-r11, lr}.

So before disable cache, first flush D-Cache.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Hongbo Zhang <hongbo.zhang@nxp.com>
Cc: York Sun <york.sun@nxp.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Tom Rini <trini@konsulko.com>
---
 arch/arm/cpu/armv7/psci.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/cpu/armv7/psci.S b/arch/arm/cpu/armv7/psci.S
index 6a36208..95b962d 100644
--- a/arch/arm/cpu/armv7/psci.S
+++ b/arch/arm/cpu/armv7/psci.S
@@ -258,6 +258,10 @@ ENDPROC(psci_enable_smp)
 ENTRY(psci_cpu_off_common)
 	push	{lr}
 
+	bl	psci_v7_flush_dcache_all
+
+	clrex					@ Why???
+
 	mrc	p15, 0, r0, c1, c0, 0		@ SCTLR
 	bic	r0, r0, #(1 << 2)		@ Clear C bit
 	mcr	p15, 0, r0, c1, c0, 0		@ SCTLR
-- 
2.6.2

[U-Boot] armv7: psci: cpu_off: flush D-Cache before disable D-Cache

[Tom Rini]

On Tue, Nov 22, 2016 at 07:41:09PM +0800, Peng Fan wrote:

> Before disable cache, need to first flush cache.
> 
> There maybe dirty data in D-Cache before disable D-Cache.
> After disable D-Cache, the first store instructions in
> psci_v7_flush_dcache_all will directly store registers
> {r4-r5, r7, r9-r11, lr} to memory.
> If there is dirty data before disable D-Cache,
> psci_v7_flush_dcache_all will flush data to memory,
> and may overwrite the memory that hold the registers
> {r4-r5, r7, r9-r11, lr}.
> 
> So before disable cache, first flush D-Cache.
> 
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> Cc: Albert Aribaud <albert.u.boot@aribaud.net>
> Cc: Chen-Yu Tsai <wens@csie.org>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Hongbo Zhang <hongbo.zhang@nxp.com>
> Cc: York Sun <york.sun@nxp.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Tom Rini <trini@konsulko.com>

Applied to u-boot/master, thanks!

-- 
Tom
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