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From: Mike Turquette <mturquette@ti.com>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 05/11] OMAPDSS: add clk_prepare and clk_unprepare
Date: Wed, 27 Jun 2012 00:47:10 +0000	[thread overview]
Message-ID: <20120627004709.GA22766@gmail.com> (raw)
In-Reply-To: <1340630090.3395.85.camel@deskari>

On 20120625-16:14, Tomi Valkeinen wrote:
> A question about clk_prepare/unprepare, not directly related: let's say
> I have a driver for some HW block. The driver doesn't use clk functions,
> but uses runtime PM. The driver also sets pm_runtime_irq_safe().
> 
> Now, the driver can call pm_runtime_get_sync() in an atomic context, and
> this would lead to the underlying framework (hwmod, omap_device, I don't
> know who =) enabling the func clock for that HW. But this would happen
> in atomic context, so the underlying framework can't use clk_prepare.
> 
> How does the underlying framework handle that case? (sorry if that's a
> stupid question =).
> 

I think it's a good question!

If we're going to call clk_prepare_enable from within a runtime pm
callback then I think we'll need to check if _irq_safe() is set and
conditionally call only clk_enable in such a case.

I'm not a runtime pm expert, but if the driver owns the responsibility
of calling pm_runtime_irq_safe then the driver has the proper context
to know that it should call clk_prepare BEFORE calling
pm_runtime_get_sync.

However if some other framework (outside of the driver) calls
pm_runtime_irq_safe then it will be difficult for the driver to know
what to do...

Regards,
Mike

>  Tomi
> 



  parent reply	other threads:[~2012-06-27  0:47 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1340372890-10091-1-git-send-email-rnayak@ti.com>
2012-06-22 13:51 ` [PATCH 05/11] OMAPDSS: add clk_prepare and clk_unprepare Rajendra Nayak
2012-06-25  6:07   ` Tomi Valkeinen
2012-06-25  7:11     ` Rajendra Nayak
2012-06-25  7:58       ` Tomi Valkeinen
2012-06-25 11:52         ` Rajendra Nayak
2012-06-25 13:14           ` Tomi Valkeinen
2012-06-26  5:12             ` Rajendra Nayak
2012-06-26  6:55               ` Tomi Valkeinen
2012-06-26  7:48                 ` Rajendra Nayak
2012-06-27  0:47             ` Mike Turquette [this message]
2012-06-27  4:19               ` Tomi Valkeinen
2012-06-27  5:31                 ` Rajendra Nayak
2012-06-25 11:22     ` Russell King - ARM Linux

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