linux-kernel - Re: [PATCH/RFC v2] ARM: amba: Remove AMBA level regulator support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 2 Apr 2012 00:33:20 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Russell King <linux@....linux.org.uk>,
	Grant Likely <grant.likely@...retlab.ca>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	linux-arm-kernel@...ts.infradead.org,
	spi-devel-general@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH/RFC v2] ARM: amba: Remove AMBA level regulator support

On Sun, Apr 1, 2012 at 11:27 PM, Mark Brown
<broonie@...nsource.wolfsonmicro.com> wrote:
> On Sun, Apr 01, 2012 at 09:22:50PM +0200, Linus Walleij wrote:
>
>> Combined with the PL022 patch this causes a power regression since
>> the PL022 is hereafter always on.
>
> I guess this code isn't in mainline, though?  In that case you can
> always add a revert of this commit to your out of tree patches if you
> need to.

No, we can sure live with it... Out-of-mainline we do use power domains
so that's what we should do instead. It currently looks like this:
http://www.igloocommunity.org/gitweb/?p=kernel/igloo-kernel.git;a=blob;f=arch/arm/mach-ux500/pm/runtime.c;hb=HEAD

It's a really nice piece of code but uses some out-of-tree features,
the most obvious one is "atomic regulators" (which are exactly
that).

>> But to the defence: power domain code was not in the kernel
>> when the AMBA "vcore" regulator was introduced so how else
>> could we do it... except for inventing power domains...
>
> Which might've happened sooner if we'd noticed :)  There were some other
> platforms doing similar things but they mostly used the clock API since
> it was always entirely platform code until 3.4 so they're less intrusive
> into the generic code.

Yeah ... but this sounds familiar, (searching searching) Yes! We did ask on
the lists if regulators were proper for modeling power domains in 2008:
http://marc.info/?l=linux-arm-kernel&m=121580531500758&w=2

But I should've pushed for a proper answer ...

Yours,
Linus Walleij
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/