linux-kernel - Re: [PATCH] clk: shmobile: div6: Avoid division by zero in .round

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Date:	Thu, 05 Feb 2015 01:14:46 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Mike Turquette <mturquette@...aro.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Geert Uytterhoeven <geert+renesas@...der.be>
CC:	Stephen Boyd <sboyd@...eaurora.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Ulrich Hecht <ulrich.hecht+renesas@...il.com>,
	Wolfram Sang <wsa@...g-engineering.com>,
	linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: shmobile: div6: Avoid division by zero in .round_rate()

Hello.

On 02/05/2015 01:04 AM, Sergei Shtylyov wrote:

>>>>> Anyone may call clk_round_rate() with a zero rate value, so we have to
>>>>> protect against that.

>>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>

>>>> Acked-by: Wolfram Sang <wsa+renesas@...g-engineering.com>

>>>> I agree that this should not be fixed in the core because the fixup is
>>>> really driver dependant.

>>>      Dunno, zero frequency seems generally insane to me.

>> It is useful to find the lowest frequency a clock can support. Basically
>> it is a search for the floor frequency.

>     Why not just use 1? Or are you assuming that some hardware could actually
> support 0 Hz?

    Replying to myself: yes, this has happened to me, when I forgot to 
override the EXTAL frequency in the board .dts file (default was 0).

>> Regards,
>> Mike

WBR, Sergei

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