The patch titled
arm: fix for Atmel AT91 powersaving
has been added to the -mm tree. Its filename is
arm-fix-for-atmel-at91-powersaving.patch
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Subject: arm: fix for Atmel AT91 powersaving
From: Andrei Birjukov <andrei.birjukov@xxxxxxxxxxxxxx>
We've discovered that our AT91SAM9260 board consumed too much power when
returning from a slowclock low-power mode. RAM self-refresh is enabled in
a bootloader in our case, this is how we saw a difference. Estimated ca.
30mA more on 4V battery than the same state before powersaving.
After a small research we found that there seems to be a bogus
sdram_selfrefresh_disable() call at the end of at91_pm_enter() call, which
overwrites the LPR register with uninitialized value. Please find the
suggested patch attached.
This patch fixes correct restoring of LPR register of the Atmel AT91 SDRAM
controller when returning from a power saving mode.
Signed-off-by: Andrei Birjukov <andrei.birjukov@xxxxxxxxxxxxxx>
Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Cc: Andrew Victor <linux@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm/mach-at91/pm.c | 1 -
1 file changed, 1 deletion(-)
diff -puN arch/arm/mach-at91/pm.c~arm-fix-for-atmel-at91-powersaving arch/arm/mach-at91/pm.c
--- a/arch/arm/mach-at91/pm.c~arm-fix-for-atmel-at91-powersaving
+++ a/arch/arm/mach-at91/pm.c
@@ -332,7 +332,6 @@ static int at91_pm_enter(suspend_state_t
at91_sys_read(AT91_AIC_IPR) & at91_sys_read(AT91_AIC_IMR));
error:
- sdram_selfrefresh_disable();
target_state = PM_SUSPEND_ON;
at91_irq_resume();
at91_gpio_resume();
_
Patches currently in -mm which might be from andrei.birjukov@xxxxxxxxxxxxxx are
arm-fix-for-atmel-at91-powersaving.patch
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