From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from nasmtp01.atmel.com ([192.199.1.245]:27258 "EHLO DVREDG01.corp.atmel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753078Ab3GPIAu (ORCPT ); Tue, 16 Jul 2013 04:00:50 -0400 Message-ID: <51E4FC4E.2010203@atmel.com> Date: Tue, 16 Jul 2013 15:54:54 +0800 From: Josh Wu MIME-Version: 1.0 To: Maxime Ripard CC: , , , , Subject: Re: [PATCH 1/5] iio: at91: use adc_clk_khz to make the calculation not easy to large than u32. References: <1373789069-11604-1-git-send-email-josh.wu@atmel.com> <1373789069-11604-2-git-send-email-josh.wu@atmel.com> <20130715125213.GB2962@lukather> In-Reply-To: <20130715125213.GB2962@lukather> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org Hi, Maxime On 7/15/2013 8:52 PM, Maxime Ripard wrote: > Hi Josh, > > On Sun, Jul 14, 2013 at 04:04:25PM +0800, Josh Wu wrote: >> for example, if adc_clk is 20Mhz and start-up time set as larger than 215us. >> then the calculation "st->startup_time * adc_clk_khz" will out of u32. >> >> In this patch, it will use khz unit for adc_clk, that avoids above problem. >> >> Signed-off-by: Josh Wu > Maybe we can have a slightly better commit log here, like: > > ------8<----------- > iio: at91: Fix adc_clk overflow > > The adc_clk variable is currently defined using a 32-bits unsigned > integer, which will overflow under some very valid range of operations. > > Such overflow will occur if, for example, the parent clock is set to a > 20MHz frequency and the ADC startup time is larger than 215ns. > > To fix this, introduce an intermediate variable holding the clock rate > in kHz. > > --------8<--------------- > > Or something like that. > > For the patch itself, I'm happy about it. You can add my Acked-by. Thank you. Your commit log is better. I will fix the commit log base on your commit in next version. > > Thanks! > Maxime > Best Regards, Josh Wu From mboxrd@z Thu Jan 1 00:00:00 1970 From: josh.wu@atmel.com (Josh Wu) Date: Tue, 16 Jul 2013 15:54:54 +0800 Subject: [PATCH 1/5] iio: at91: use adc_clk_khz to make the calculation not easy to large than u32. In-Reply-To: <20130715125213.GB2962@lukather> References: <1373789069-11604-1-git-send-email-josh.wu@atmel.com> <1373789069-11604-2-git-send-email-josh.wu@atmel.com> <20130715125213.GB2962@lukather> Message-ID: <51E4FC4E.2010203@atmel.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, Maxime On 7/15/2013 8:52 PM, Maxime Ripard wrote: > Hi Josh, > > On Sun, Jul 14, 2013 at 04:04:25PM +0800, Josh Wu wrote: >> for example, if adc_clk is 20Mhz and start-up time set as larger than 215us. >> then the calculation "st->startup_time * adc_clk_khz" will out of u32. >> >> In this patch, it will use khz unit for adc_clk, that avoids above problem. >> >> Signed-off-by: Josh Wu > Maybe we can have a slightly better commit log here, like: > > ------8<----------- > iio: at91: Fix adc_clk overflow > > The adc_clk variable is currently defined using a 32-bits unsigned > integer, which will overflow under some very valid range of operations. > > Such overflow will occur if, for example, the parent clock is set to a > 20MHz frequency and the ADC startup time is larger than 215ns. > > To fix this, introduce an intermediate variable holding the clock rate > in kHz. > > --------8<--------------- > > Or something like that. > > For the patch itself, I'm happy about it. You can add my Acked-by. Thank you. Your commit log is better. I will fix the commit log base on your commit in next version. > > Thanks! > Maxime > Best Regards, Josh Wu