linux-kernel - Re: [PATCH] spi: pl022: Add clk_{un}prepare() support in runtime PM

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Date:	Tue, 18 Sep 2012 09:39:09 +0530
From:	viresh kumar <viresh.kumar@...aro.org>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Vipul Kumar Samar <vipulkumar.samar@...com>,
	grant.likely@...retlab.ca, spi-devel-general@...ts.sourceforge.net,
	linux-arm-kernel@...ts.infradead.org, spear-devel@...t.st.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spi: pl022: Add clk_{un}prepare() support in runtime PM

On Mon, Sep 17, 2012 at 7:09 PM, Linus Walleij <linus.walleij@...aro.org> wrote:
> This driver does clk_prepare/unprepare at probe
> and removed, so I guess what you're trying to say is that
> on your platform the clk_unprepare() process context call
> is needed to save power?
>
> Please elaborate...

Hi Linus,

Yes, we don't need to call prepare() again atleast for SPEAr. You are correct.
I saw the driver after a long time :)
Can you please elaborate, why can't i see any clk_disable/enable calls anywhere
else from probe. If i remember correctly, earlier we used to enable/disable
clk after transfers and also during suspend/resume.

The amba layer is taking care of interface clock only and not
functional clock. So
i believe that's not the magic code. :)

--
viresh
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