From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Date: Fri, 06 Feb 2015 11:12:13 +0000 Subject: Re: [PATCH] clk: shmobile: div6: Avoid division by zero in .round_rate() Message-Id: <54D4A18D.3010504@cogentembedded.com> List-Id: References: <1423052841-15194-1-git-send-email-geert+renesas@glider.be> <54D29760.4010009@cogentembedded.com> <54D299D6.7060809@cogentembedded.com> <4034374.lq5RZGeRAm@avalon> In-Reply-To: <4034374.lq5RZGeRAm@avalon> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Laurent Pinchart Cc: Mike Turquette , Wolfram Sang , Geert Uytterhoeven , Stephen Boyd , Ulrich Hecht , Wolfram Sang , linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org 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 >>>>>> Acked-by: Wolfram Sang >>>>>> 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