LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.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: Thu, 05 Feb 2015 19:19:14 +0200	[thread overview]
Message-ID: <4034374.lq5RZGeRAm@avalon> (raw)
In-Reply-To: <54D299D6.7060809@cogentembedded.com>

Hi Sergei,

On Thursday 05 February 2015 01:14:46 Sergei Shtylyov wrote:
> 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@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 ;-)

Jokes aside, a zero frequency is the usual way to find the lowest frequency, 
but I agree that there aren't many integers between 0 and 1. Mike, do you have 
an opinion ?

-- 
Regards,

Laurent Pinchart


  reply	other threads:[~2015-02-05 17:18 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-04 12:27 Geert Uytterhoeven
2015-02-04 13:31 ` Sergei Shtylyov
2015-02-04 13:50   ` Laurent Pinchart
2015-02-04 17:32 ` Wolfram Sang
2015-02-04 17:45   ` Sergei Shtylyov
2015-02-04 22:01     ` Mike Turquette
2015-02-04 22:04       ` Sergei Shtylyov
2015-02-04 22:14         ` Sergei Shtylyov
2015-02-05 17:19           ` Laurent Pinchart [this message]
2015-02-05 17:46             ` Mike Turquette
2015-02-06 11:12             ` Sergei Shtylyov
2015-02-04 22:05   ` Mike Turquette

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4034374.lq5RZGeRAm@avalon \
    --to=laurent.pinchart@ideasonboard.com \
    --cc=geert+renesas@glider.be \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-sh@vger.kernel.org \
    --cc=mturquette@linaro.org \
    --cc=sboyd@codeaurora.org \
    --cc=sergei.shtylyov@cogentembedded.com \
    --cc=ulrich.hecht+renesas@gmail.com \
    --cc=wsa@sang-engineering.com \
    --cc=wsa@the-dreams.de \
    --subject='Re: [PATCH] clk: shmobile: div6: Avoid division by zero in .round_rate()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).