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From: Lee Jones <lee.jones@linaro.org>
To: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, mturquette@linaro.org,
	sboyd@codeaurora.org, kernel@stlinux.com,
	devicetree@vger.kernel.org
Subject: Re: [PATCH v3 0/4] clk: st: New always-on clock domain
Date: Fri, 27 Feb 2015 21:49:41 +0000	[thread overview]
Message-ID: <20150227214941.GB12821@x1> (raw)
In-Reply-To: <87385r3uk9.fsf@free.fr>

On Fri, 27 Feb 2015, Robert Jarzmik wrote:

> Lee Jones <lee.jones@linaro.org> writes:
> 
> > v2 => v3:
> >   - Ensure DT actually reflects h/w
> >     - i.e. Nodes should not contain a mishmash of different IP
> >       blocks, but should identify related h/w.  In the current
> >       example we use interconnects
> >   - Change naming from clkdomain to clk-always-on
> >   - Place "do not abuse" warning in documentation
> >
> > v1 => v2:
> >   - Turned the ST specific driver into a generic one
> >   
> > Hardware can have a bunch of clocks which must not be turned off.
> > If drivers a) fail to obtain a reference to any of these or b) give
> > up a previously obtained reference during suspend, the common clk
> > framework will attempt to turn them off and the hardware will
> > subsequently die.  The only way to recover from this failure is to
> > restart.
> >   
> > To avoid either of these two scenarios from catastrophically
> > disabling the running system we have implemented a clock domain
> > where clocks are consumed and references are taken, thus preventing
> > them from being shut down by the framework.
> 
> Hi Lee,
> 
> I wonder why there is a need for a new clock when CLK_IGNORE_UNUSED does
> exist. What is the usecase that is covered by this patchset which is not used by
> CLK_IGNORE_UNUSED clock flag ?
> 
> And if that reason exists, I'd like to find it in the commit message.

The problem is applying that flag in a generic way.

However, I guess you haven't seen this [1] yet?

[1] https://lkml.org/lkml/2015/2/27/548

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

  reply	other threads:[~2015-02-27 21:49 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-24 17:33 Lee Jones
2015-02-24 17:33 ` [PATCH v3 1/4] ARM: sti: stih407-family: Supply defines for CLOCKGEN A0 Lee Jones
2015-02-24 17:33 ` [PATCH v3 2/4] ARM: sti: stih407-family: Add platform interconnects to always-on clk domain Lee Jones
2015-02-24 17:33 ` [PATCH v3 3/4] clk: Provide an always-on clock domain framework Lee Jones
2015-02-24 17:33 ` [PATCH v3 4/4] clk: dt: Introduce always-on clock domain documentation Lee Jones
2015-02-24 17:42 ` [PATCH v3 0/4] clk: st: New always-on clock domain Lee Jones
2015-02-27 21:37 ` Robert Jarzmik
2015-02-27 21:49   ` Lee Jones [this message]
2015-02-27 23:38     ` Robert Jarzmik
2015-03-02  8:30       ` Lee Jones
2015-03-02 11:29         ` Robert Jarzmik
2015-03-02 11:37           ` Lee Jones
2015-03-04 12:00 ` Lee Jones
2015-03-06 19:08   ` Mike Turquette
2015-03-09  9:28     ` Lee Jones
2015-03-25  4:11       ` Geert Uytterhoeven
2015-03-26 13:51         ` Lee Jones
2015-03-26 16:55           ` Geert Uytterhoeven
2015-03-26 19:38             ` Lee Jones
2015-04-02  8:31               ` Geert Uytterhoeven
2015-04-02 10:48                 ` Lee Jones

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