linux-kernel - Re: [PATCH RFC RFT 0/3] clk: detect per-user enable imbalances and implement hand-off

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Date:	Tue, 11 Aug 2015 19:42:59 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Michael Turquette <mturquette@...libre.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-clk@...r.kernel.org, Stephen Boyd <sboyd@...eaurora.org>,
	Lee Jones <lee.jones@...aro.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Sascha Hauer <s.hauer@...gutronix.de>
Subject: Re: [PATCH RFC RFT 0/3] clk: detect per-user enable imbalances and
 implement hand-off

Hi Mike,

On Tue, Aug 11, 2015 at 6:41 PM, Michael Turquette
<mturquette@...libre.com> wrote:
> Quoting Geert Uytterhoeven (2015-08-11 02:20:12)
>> On Fri, Aug 7, 2015 at 9:09 PM, Michael Turquette
>> <mturquette@...libre.com> wrote:
>> > This is an alternative solution to Lee's "clk: Provide support for
>> > always-on clocks" series[0].

>> I gave it a try on r8a7791/koelsch, where I replaced the hack from
>> "[PATCH/RFC 1/5] clk: shmobile: mstp: Never disable INTC-SYS"
>> (http://www.spinics.net/lists/linux-sh/msg41107.html) by setting
>>
>>         init.flags |= CLK_ENABLE_HAND_OFF
>>
>> in cpg_mstp_clock_register() for "intc-sys".
>>
>> The end result is fine (the "intc-sys" clock is never disabled), but I get
>> a few annoying lockdep splats like below (one for the "intc-sys" clock,
>> and one more for each parent up to the root clock):
>>
>> ------------[ cut here ]------------
>> WARNING: CPU: 0 PID: 0 at drivers/clk/clk.c:745 clk_core_enable+0x6c/0xdc()

> Thanks much for testing! I forgot to hold the enable lock in __clk_init
> (we already hold the prepare lock). Can you tell me if this diff fixes
> it?

Yes it does. Thanks for the quick fix!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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