linux-kernel - Re: [PATCH v2 0/2] Firmware-assisted suspend/resume of Exynos SoCs

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Message-ID: <53DA941A.4070801@gmail.com>
Date:	Thu, 31 Jul 2014 21:08:10 +0200
From:	Tomasz Figa <tomasz.figa@...il.com>
To:	Tomasz Figa <t.figa@...sung.com>, linux-samsung-soc@...r.kernel.org
CC:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Arnd Bergmann <arnd@...db.de>, swarren@...dia.com,
	acourbot@...dia.com, Marek Szyprowski <m.szyprowski@...sung.com>,
	Olof Johansson <olof@...om.net>, drake@...lessm.com
Subject: Re: [PATCH v2 0/2] Firmware-assisted suspend/resume of Exynos SoCs

Hi Kukjin,

On 17.07.2014 17:56, Tomasz Figa wrote:
> On Exynos-based boards running secure firmware the sequence of low level
> operations to enter and leave system-wide sleep mode is different than
> on those without the firmware. Namely:
>  - CP15 power control and diagnostic registers cannot be written directly,
>  - the way of setting boot address and boot flag is different,
>  - different resume handler needs to be used,
>  - dedicated SMC call needs to be performed instead of letting the CPU enter
>    WFI.
> 
> This series introduces .suspend() and .resume() firmware operations to
> perform low level firmware-specific suspend and resume and then leverages
> them to provide suspend-resume path meeting the above requirements.
> 
> The series is based on Kgene's for-next branch and tested on:
>  - Exynos4412-based Trats2 board running in non-secure mode (under secure
>    firmware) with few board-specific fixes that will be sent separately soon,
>  - Exynos4210-based Trats board running in secure mode,
>  - Exynos4412-based ODROID-U3 board running in non-secure mode with one minor
>    board-specific fix which will be send shortly.
> 
> Depends on:
>  - [PATCH v3] ARM: save/restore Cortex-A9 CP15 registers on suspend/resume
>    (http://www.spinics.net/lists/arm-kernel/msg346212.html)
>  - [PATCH v3] ARM: EXYNOS: Fix suspend/resume sequences
>    (https://lkml.org/lkml/2014/7/15/319)
>  - [PATCH] ARM: make it easier to check the CPU part number correctly
>    (http://thread.gmane.org/gmane.linux.ports.arm.kernel/335126
>     already in linux-next)
> 
> Changes since v1:
>  - dropped outer_resume() - will be handled in assembly in further patches,
>    as support for L2C in non-secure mode gets added,
>  - moved CP15 resume to assembly as it needs to be done before MMU is enabled,
>  - surrounded CP15 save with a check for cpuid part, because it is valid only
>    on Cortex A9,
>  - rebased on next-20140717 tag of linux-next tree.
> 
> Tomasz Figa (2):
>   ARM: firmware: Introduce suspend and resume operations
>   ARM: EXYNOS: Add support for firmware-assisted suspend/resume
> 
>  Documentation/arm/firmware.txt  | 28 +++++--------------------
>  arch/arm/include/asm/firmware.h |  8 ++++++++
>  arch/arm/mach-exynos/Makefile   |  1 +
>  arch/arm/mach-exynos/common.h   |  4 ++++
>  arch/arm/mach-exynos/firmware.c | 45 +++++++++++++++++++++++++++++++++++++++++
>  arch/arm/mach-exynos/pm.c       | 16 ++++++++++-----
>  arch/arm/mach-exynos/sleep.S    | 28 +++++++++++++++++++++++++
>  arch/arm/mach-exynos/smc.h      |  4 ++++
>  8 files changed, 106 insertions(+), 28 deletions(-)
> 

I wonder if it is already too late to take this rather useful series for
3.17 as well...

Best regards,
Tomasz
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