linux-kernel - Re: [PATCH v7 2/3] clk: introduce the common clock framework

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Date:	Fri, 23 Mar 2012 14:39:53 -0700
From:	"Turquette, Mike" <mturquette@...com>
To:	Saravana Kannan <skannan@...eaurora.org>
Cc:	Shawn Guo <shawn.guo@...aro.org>, Paul Walmsley <paul@...an.com>,
	Russell King <linux@....linux.org.uk>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	patches@...aro.org, Magnus Damm <magnus.damm@...il.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org, linaro-dev@...ts.linaro.org,
	Jeremy Kerr <jeremy.kerr@...onical.com>,
	linux-arm-kernel@...ts.infradead.org,
	Arnd Bergman <arnd.bergmann@...aro.org>
Subject: Re: [PATCH v7 2/3] clk: introduce the common clock framework

On Fri, Mar 23, 2012 at 2:33 PM, Saravana Kannan <skannan@...eaurora.org> wrote:
> On 03/20/2012 08:10 PM, Saravana Kannan wrote:
>>
>> On 03/20/2012 04:53 PM, Turquette, Mike wrote:
>>>
>>> It does make me
>>> wonder if it would be a good idea to pass in the parent rate for
>>> .set_parent, which is analogous to .set_rate in many ways.
>>
>>
>> I need to think a bit more about this.
>
>
> I was thinking about this. I think the common clock fwk should let the
> set_parent ops "return" the rate of the clock in addition to passing the
> rate of the parent in.
>
> Say this is a divider clock and some one changes the parent. The cached
> "rate" of the clock in the clock fwk is no longer correct. So, the clock fwk
> should also add a "*new_rate" param to set parent ops.

__clk_recalc_rates is called by __clk_reparent which is called by
clk_set_parent.  __clk_recalc_rates is also called by clk_set_rate.

Does this not handle the old cached clk->rate for you?

Thanks,
Mike

>
> Thanks,
>
> Saravana
>
> --
> Sent by an employee of the Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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