From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Ferre Subject: Re: [PATCH] ARM: at91: sama5d3: reduce TWI internal clock frequency Date: Fri, 22 Nov 2013 16:09:46 +0100 Message-ID: <528F73BA.2080601@atmel.com> References: <1385129228-11225-1-git-send-email-ludovic.desroches@atmel.com> <20131122143350.GA7420@katana> <20131122145141.GB30749@ludovic.desroches@atmel.com> <20131122145835.GB7420@katana> <20131122150734.GC30749@ludovic.desroches@atmel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20131122150734.GC30749-tOglhBvtKaELqBSMlTbpHvU/3Eu2kcEP@public.gmane.org@atmel.com> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, plagnioj-sclMFOaUSTBWk0Htik3J/w@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Ludovic Desroches List-Id: linux-i2c@vger.kernel.org On 22/11/2013 16:07, Ludovic Desroches : > On Fri, Nov 22, 2013 at 03:58:35PM +0100, Wolfram Sang wrote: >> On Fri, Nov 22, 2013 at 03:51:41PM +0100, Ludovic Desroches wrote: >>> Hi Wolfram, >>> >>> On Fri, Nov 22, 2013 at 03:33:51PM +0100, Wolfram Sang wrote: >>>> On Fri, Nov 22, 2013 at 03:07:08PM +0100, ludovic.desroches-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org wrote: >>>>> From: Ludovic Desroches >>>>> >>>>> There are still I2C unexpected behaviors which are solved by reducing TWI >>>>> internal frequency. >>>>> >>>>> Cc: #3.10+ >>>>> Signed-off-by: Ludovic Desroches >>>> >>>> I think the commit message needs more details. Is this a true bugfix >>>> because the real bus frequency was too high because of the wrong >>>> divider? Is this a workaround which makes things work but will make the >>>> bus frequency slower than it should be? >>> >>> This fix doesn't concern the i2c bus frequency, only the internal IP frequency. >>> >>> TWI has been validated at 66MHz. With some devices, transfer hangs during i2c >>> frame transmission. This issue disappears when reducing the internal frequency >>> of the IP. Maybe there is some oversampling on i2c signals. >>> Unfortunately, I have no clear status about the root cause that's why >>> the commit message was imprecise. >> >> This paragraph is a way better commit message IMO :) >> > > Ok I'll update it. Ludo, you can also add my: Acked-by: Nicolas Ferre Bye, > Thanks for the review Wolfram. > > Regards > > Ludovic > > -- Nicolas Ferre