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From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Doug Anderson <dianders@chromium.org>
Cc: Mike Turquette <mturquette@linaro.org>,
	Heiko Stuebner <heiko@sntech.de>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] clk: Propagate prepare and enable when reparenting orphans
Date: Sat, 8 Nov 2014 00:23:34 +0000	[thread overview]
Message-ID: <20141108002334.GT4042@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <CAD=FV=WCwGjuLNFPANqqq-+rEN_jhqi+Bfss2ugDJEgjf3z_Gg@mail.gmail.com>

On Fri, Nov 07, 2014 at 04:14:23PM -0800, Doug Anderson wrote:
> Russell,
> I guess I'm still confused.  My patch continues to be about orphans
> and I don't see the bug you are pointing to.

Ah, in which case, the question changes: how can an orphaned clock be
succesfully prepared and enabled?

Drivers expect that a clock for which clk_enable() has returned
successfully _will_ at that point be supplying the clock.  If we don't
yet know it's parent, how do we know that it will be supplying that
clock?

What about a driver calling clk_set_rate() on an orphaned clock?

>From what I can see (__clk_reparent will re-set the child's clock when
reparenting) having a driver able to claim an orphaned clock, let
alone prepare and enable it, looks rather buggy to me.

-- 
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.

  reply	other threads:[~2014-11-08  0:23 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-07 18:51 Doug Anderson
2014-11-07 18:58 ` Russell King - ARM Linux
2014-11-07 22:52   ` Doug Anderson
2014-11-07 23:36     ` Russell King - ARM Linux
2014-11-08  0:14       ` Doug Anderson
2014-11-08  0:23         ` Russell King - ARM Linux [this message]
2014-11-08  0:46           ` Doug Anderson

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