linux-kernel - Re: [PATCH v3 0/2] clk: improve handling of orphan clocks

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Date:	Fri, 8 May 2015 12:02:47 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	Kevin Hilman <khilman@...nel.org>,
	Heiko Stübner <heiko@...ech.de>,
	Mike Turquette <mturquette@...aro.org>,
	Doug Anderson <dianders@...omium.org>,
	linux-clk@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	Alex Elder <elder@...aro.org>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Max Filippov <jcmvbkbc@...il.com>,
	Sascha Hauer <kernel@...gutronix.de>,
	Zhangfei Gao <zhangfei.gao@...aro.org>,
	Santosh Shilimkar <ssantosh@...nel.org>,
	Chao Xie <chao.xie@...vell.com>,
	Jason Cooper <jason@...edaemon.net>,
	Stefan Wahren <stefan.wahren@...e.com>,
	Andrew Bresticker <abrestic@...omium.org>,
	Robert Jarzmik <robert.jarzmik@...e.fr>,
	Georgi Djakov <georgi.djakov@...aro.org>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Barry Song <baohua@...nel.org>,
	Dinh Nguyen <dinguyen@...nsource.altera.com>,
	Viresh Kumar <viresh.linux@...il.com>,
	Gabriel FERNANDEZ <gabriel.fernandez@...com>,
	Emilio López <emilio@...pez.com.ar>,
	Peter De Sc hrijver <pdeschrijver@...dia.com>,
	Tero Kristo <t-kristo@...com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Pawel Moll <pawel.moll@....com>,
	Michal Simek <michal.simek@...inx.com>,
	Olof Johansson <olof@...om.net>,
	Tyler Baker <tyler.baker@...aro.org>
Subject: Re: [PATCH v3 0/2] clk: improve handling of orphan clocks

On Thu, May 07, 2015 at 02:03:57PM -0700, Stephen Boyd wrote:
> On 05/07/15 08:17, Kevin Hilman wrote:
> > On Fri, May 1, 2015 at 4:40 PM, Stephen Boyd <sboyd@...eaurora.org> wrote:
> >> On 05/01/15 15:07, Heiko Stübner wrote:
> >>> Am Freitag, 1. Mai 2015, 13:52:47 schrieb Stephen Boyd:
> >>>
> >>>>> Instead I guess we could hook it less deep into clk_get_sys, like in the
> >>>>> following patch?
> >>>> It looks like it will work at least, but still I'd prefer to keep the
> >>>> orphan check contained to clk.c. How about this compile tested only patch?
> >>> I gave this a spin on my rk3288-firefly board. It still boots, the clock tree
> >>> looks the same and it also still defers nicely in the scenario I needed it
> >>> for. The implementation also looks nice - and of course much more compact than
> >>> my check in two places :-) . I don't know if you want to put this as follow-up
> >>> on top or fold it into the original orphan-check, so in any case
> >>>
> >>> Tested-by: Heiko Stuebner <heiko@...ech.de>
> >>> Reviewed-by: Heiko Stuebner <heiko@...ech.de>
> >> Thanks. I'm leaning towards tossing your patch 2/2 and replacing it with
> >> my patch and a note that it's based on an earlier patch from you.
> > It appears this has landed in linux-next in the form of 882667c1fcf1
> > clk: prevent orphan clocks from being used.  A bunch of boot failures
> > for sunxi in today's linux-next[1] were bisected down to that patch.
> >
> > I confirmed that reverting that commit on top of next/master gets
> > sunxi booting again.
> >
> >
> 
> Thanks for the report. I've removed the two clk orphan patches from
> clk-next. Would it be possible to try with next-20150507 and
> clk_ignore_unused on the command line?

This makes it work, but it's not really an option.

> Also we can try to see if critical clocks aren't being forced on by
> applying this patch and looking for clk_get() failures

And that shows that the CPU and DDR clocks are not protected, which
obviously is pretty mad.

I've mass converted all our probing code to use OF_CLK_DECLARE, and
make things work again.

http://code.bulix.org/5goa5j-88345?raw

Is this an acceptable solution?

We were already moving to this, I'm not really fond of doing this like
that, but I guess this whole debacle makes it necessary.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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