linux-kernel - Re: [PATCH] clk: divider: fix rate calculation for fractional rates

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Message-ID: <52E78930.8080607@ti.com>
Date:	Tue, 28 Jan 2014 12:40:48 +0200
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	Mike Turquette <mturquette@...aro.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	"Kristo, Tero" <t-kristo@...com>
Subject: Re: [PATCH] clk: divider: fix rate calculation for fractional rates

On 2014-01-28 12:32, Russell King - ARM Linux wrote:

>> Why I'm asking this is that for me (and probably for others also if
>> you've seen it used in the kernel code) it feels natural to have code like:
>>
>> 	rate = clk_round_rate(clk, rate);
>> 	
>> 	/* Verify the rounded rate here to see it's ok for the IP etc */
>>
>> 	/* The rate is ok, so set it */
>> 	clk_set_rate(clk, rate);
> 
> If you want to do something with the rounded rate, then that's fine,
> you have a reason to do it this way.  However, what I was referring to
> are drivers which literally do this:
> 
> 	clk_set_rate(clk, clk_round_rate(clk, rate));

Thanks for clarification. Agreed, that's pointless. I gave the sequence
in the patch description just as an example for the sake of discussion
about the bug.

I didn't realize people actually do that in real code =).

 Tomi



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