From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ludovic Desroches <ludovic.desroches@atmel.com>
Subject: Re: [PATCH] ARM: at91: sama5d3: reduce TWI internal clock frequency
Date: Fri, 22 Nov 2013 16:07:34 +0100
Message-ID: <21404.4217639186$1385132894@news.gmane.org>
References: <1385129228-11225-1-git-send-email-ludovic.desroches@atmel.com>
 <20131122143350.GA7420@katana>
 <20131122145141.GB30749@ludovic.desroches@atmel.com>
 <20131122145835.GB7420@katana>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org>
Content-Disposition: inline
In-Reply-To: <20131122145835.GB7420@katana>
List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-arm-kernel>,
 <mailto:linux-arm-kernel-request@lists.infradead.org?subject=unsubscribe>
List-Archive: <http://lists.infradead.org/pipermail/linux-arm-kernel/>
List-Post: <mailto:linux-arm-kernel@lists.infradead.org>
List-Help: <mailto:linux-arm-kernel-request@lists.infradead.org?subject=help>
List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-arm-kernel>,
 <mailto:linux-arm-kernel-request@lists.infradead.org?subject=subscribe>
Sender: "linux-arm-kernel" <linux-arm-kernel-bounces@lists.infradead.org>
Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org
To: Wolfram Sang <wsa@the-dreams.de>
Cc: plagnioj@jcrosoft.com, Ludovic Desroches <ludovic.desroches@atmel.com>, nicolas.ferre@atmel.com, linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org
List-Id: linux-i2c@vger.kernel.org

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@atmel.com wrote:
> > > > From: Ludovic Desroches <ludovic.desroches@atmel.com>
> > > > 
> > > > There are still I2C unexpected behaviors which are solved by reducing TWI
> > > > internal frequency.
> > > > 
> > > > Cc: <stable@vger.kernel.org> #3.10+
> > > > Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
> > > 
> > > 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.

Thanks for the review Wolfram.

Regards

Ludovic