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

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Date:	Tue, 12 May 2015 15:35:50 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
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 05/08/15 03:02, Maxime Ripard wrote:
> 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.
>

Hmm.. I thought it didn't fix it for Kevin. Confused.

>> 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.
>

I wonder why we can't switch out the clk_ops on the affected platforms +
clocks to be read-only (at least for the enable/disable part)? That
would fix it just the same right? I wasn't around for the original
discussion regarding this always-on stuff so perhaps I've missed something.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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