[PATCH 3/7] powerpc/85xx: add sleep and deep sleep support

[Li Yang-R58472]

>To: Zhao Chenhui-B35336; linuxppc-dev at lists.ozlabs.org
>Subject: Re: [PATCH 3/7] powerpc/85xx: add sleep and deep sleep support
>
>Hi Zhao,
>
>From: Li Yang <leoli at freescale.com>
>
>Some Freescale chips like MPC8536 and P1022 has deep sleep PM mode in
>addtion to the sleep PM mode.
>
>In sleep PM mode, the clocks of e500 core and unused IP blocks is turned
>off. IP blocks which are allowed to wake up the processor are still
>running
>
>While in deep sleep PM mode, additionally, the power supply is removed
>from e500 core and most IP blocks. Only the blocks needed to wake up the
>chip out of deep sleep are ON.
>
>This patch supports 32-bit and 36-bit address space.
>
>The deep sleep mode is equal to the Suspend-to-RAM state of Linux Power
>Management.
>
>Command to enter deep sleep mode.
>  echo mem > /sys/power/state
>
>
>Thanks a lot for bringing this code to mainline. I was recently involved
>in enabling deep sleep on a custom P1022 board, and would like to make
>some remarks based on this experience.
>
>1. I think 85xx deep sleep code would be more complete if you also port
>FSL
>    BSP code that saves eLBC configuration before entering deep sleep and
>    restores it afterwards. Otherwise all eLBC customization done by u-
>boot is lost.

Thanks for the comment.  That work is also being considered for upstream, but not in this series.

>
>2. You should implement fsl_deep_sleep() routine for 85xx. The default
>implementation
>    in include/linux/fsl_devices.h always returns 0. The routine is used
>by FSL USB host
>    driver, drivers/usb/host/ehci-fsl.c to restore USB hardware state
>after deep sleep.
>    With default implementation USB is dead on 85xx after deep sleep if
>USB PHY is
>    powered down completely.

Added to the to-do list.  Thanks.

- Leo