Re: [PATCH 0/4] Enable PM and PM_GENERIC_DOMAINS for SoCs with PM Domains

From: Simon Horman <horms@verge.net.au>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/4] Enable PM and PM_GENERIC_DOMAINS for SoCs with PM Domains
Date: Wed, 17 Feb 2016 12:18:41 +0000	[thread overview]
Message-ID: <20160217121840.GC346@verge.net.au> (raw)
In-Reply-To: <1455636712-3040-1-git-send-email-geert+renesas@glider.be>

On Tue, Feb 16, 2016 at 04:31:48PM +0100, Geert Uytterhoeven wrote:
> 	Hi Simon, Magnus,
> 
> All supported Renesas ARM SoCs (except for Emma Mobile EV2) have clock
> domains. Some SoCs also have power domains. To ensure proper operation
> of on-SoC modules, module clocks must be ungated, and power domains must
> be powered up when needed.
> 
> Currently the user can choose to build a kernel with power management
> enabled or disabled:
>   - If CONFIG_PM=y, power domains and/or module clocks are handled
>     dynamically by Runtime PM and the generic power domain.
>   - If CONFIG_PM=n, power domains are assumed to be powered up by reset
>     state or by the boot loader, and module clocks are handled by the
>     legacy clock domain on driver (un)bind.
>     The latter is implemented using a platform bus notifier, which
>     applies not only to all on-SoC devices, but to all platform devices
>     present in the system.
> 
> To remove the dependency on implicit assumptions, and to get rid of the
> peculiarities of the legacy clock domain, enable CONFIG_PM and
> CONFIG_PM_GENERIC_DOMAINS unconditionally, for all Renesas ARM SoCs with
> clock and/or power domains.
> 
> Patches:
>   - Patches 1 and 2 enable PM and PM_GENERIC_DOMAINS,
>   - Patch 3 removes the now unused legacy clock domain code for Renesas
>     ARM SoCs,
>   - Patch 4 relieves you from maintaining drivers/sh/, which is no
>     longer used on Renesas ARM SoCs, and returns it to the SuperH
>     people.
> 
> Notes:
>   - This does cause an increase in kernel size.  Given bloat-o-meter
>     reports a modest increase of 26 KiB for an RZ/A1H kernel, this
>     should not be a problem, even when used on RZ/A1H with XIP and
>     internal RAM only.
>   - Patch 3 does break booting R-Car Gen2 boards using pre-v4.3 DTSes
>     that don't have power-domains properties,
>   - Patch 3 may unbreak SuperH-based ARCH_SHMOBILE platforms, which were
>     probably broken since v4.4 by commit 0ba58de231066e47 ("drivers: sh:
>     Get rid of CONFIG_ARCH_SHMOBILE_MULTI"),
>   - Currently CONFIG_PM=n doesn't work anyway on r8a7795 as "drivers:
>     sh: Handle PM_GENERIC_DOMAINS_OF=n with new r8a7795 CPG/MSSR
>     driver" isn't upstream.
> 
> For your convenience, I've also pushed this series to
> git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git#topic/mandatory-pm-v1
> 
> Thanks for your comments!
> 
> Geert Uytterhoeven (4):
>   ARM: shmobile: Enable PM and PM_GENERIC_DOMAINS for SoCs with PM
>     Domains
>   arm64: renesas: Enable PM and PM_GENERIC_DOMAINS for SoCs with PM
>     Domains

Thanks, I have tentatively queued up the above two patches for v4.6.

With regards to the remaining two patches, I propose deferring them
for a few releases so that we can shake out any regressions that
may occur before making a compatibility change.

>   drivers: sh: Stop using the legacy clock domain on ARM
>   MAINTAINERS: Drop drivers/sh/ for Renesas ARM
> 
>  MAINTAINERS                    |  1 -
>  arch/arm/mach-shmobile/Kconfig | 13 ++++++++-----
>  arch/arm64/Kconfig.platforms   |  3 ++-
>  drivers/Makefile               |  1 -
>  drivers/sh/pm_runtime.c        |  9 ---------
>  5 files changed, 10 insertions(+), 17 deletions(-)