From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mike Turquette <mturquette@linaro.org>,
Wolfram Sang <wsa@the-dreams.de>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Stephen Boyd <sboyd@codeaurora.org>,
Ulrich Hecht <ulrich.hecht+renesas@gmail.com>,
Wolfram Sang <wsa@sang-engineering.com>,
linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] clk: shmobile: div6: Avoid division by zero in .round_rate()
Date: Fri, 06 Feb 2015 11:12:13 +0000 [thread overview]
Message-ID: <54D4A18D.3010504@cogentembedded.com> (raw)
In-Reply-To: <4034374.lq5RZGeRAm@avalon>
Hello.
On 2/5/2015 8:19 PM, Laurent Pinchart 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@glider.be>
>>>>>> Acked-by: Wolfram Sang <wsa+renesas@sang-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).
> So it was a good thing that the driver crashed, it let you find a bug ;-)
None of the clock drivers crashed, but the SDHI driver hanged instead, and
I spent much time tracing it in order to find where it hanged. :-/
WBR, Sergei
WARNING: multiple messages have this Message-ID (diff)
From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mike Turquette <mturquette@linaro.org>,
Wolfram Sang <wsa@the-dreams.de>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Stephen Boyd <sboyd@codeaurora.org>,
Ulrich Hecht <ulrich.hecht+renesas@gmail.com>,
Wolfram Sang <wsa@sang-engineering.com>,
linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] clk: shmobile: div6: Avoid division by zero in .round_rate()
Date: Fri, 06 Feb 2015 14:12:13 +0300 [thread overview]
Message-ID: <54D4A18D.3010504@cogentembedded.com> (raw)
In-Reply-To: <4034374.lq5RZGeRAm@avalon>
Hello.
On 2/5/2015 8:19 PM, Laurent Pinchart 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@glider.be>
>>>>>> Acked-by: Wolfram Sang <wsa+renesas@sang-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).
> So it was a good thing that the driver crashed, it let you find a bug ;-)
None of the clock drivers crashed, but the SDHI driver hanged instead, and
I spent much time tracing it in order to find where it hanged. :-/
WBR, Sergei
next prev parent reply other threads:[~2015-02-06 11:12 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-04 12:27 [PATCH] clk: shmobile: div6: Avoid division by zero in .round_rate() Geert Uytterhoeven
2015-02-04 12:27 ` Geert Uytterhoeven
2015-02-04 13:31 ` Sergei Shtylyov
2015-02-04 13:31 ` Sergei Shtylyov
2015-02-04 13:50 ` Laurent Pinchart
2015-02-04 13:50 ` Laurent Pinchart
2015-02-04 17:32 ` Wolfram Sang
2015-02-04 17:32 ` Wolfram Sang
2015-02-04 17:45 ` Sergei Shtylyov
2015-02-04 17:45 ` Sergei Shtylyov
2015-02-04 22:01 ` Mike Turquette
2015-02-04 22:01 ` Mike Turquette
2015-02-04 22:04 ` Sergei Shtylyov
2015-02-04 22:04 ` Sergei Shtylyov
2015-02-04 22:14 ` Sergei Shtylyov
2015-02-04 22:14 ` Sergei Shtylyov
2015-02-05 17:19 ` Laurent Pinchart
2015-02-05 17:19 ` Laurent Pinchart
2015-02-05 17:46 ` Mike Turquette
2015-02-05 17:46 ` Mike Turquette
2015-02-06 11:12 ` Sergei Shtylyov [this message]
2015-02-06 11:12 ` Sergei Shtylyov
2015-02-04 22:05 ` Mike Turquette
2015-02-04 22:05 ` Mike Turquette
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