From mboxrd@z Thu Jan 1 00:00:00 1970 From: ludovic.desroches Subject: Re: [PATCH v11 3/4] drivers/i2c/busses/i2c-at91.c: add new driver Date: Thu, 30 Aug 2012 09:35:35 +0200 Message-ID: <503F17C7.5010807@atmel.com> References: <4f3dcfbf1e8eab3e251ab3558e9e1e9123643928.1345618760.git.n.voss@weinmann.de>, <503B4919.6080306@atmel.com> , <503B623C.4030304@atmel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: "Voss, Nikolaus" Cc: "'ben-linux@fluff.org'" , "'carsten.behling@garz-fricke.com'" , "'nicolas.ferre@atmel.com'" , "'linux-kernel@vger.kernel.org'" , "'balbi@ti.com'" , "'h.feurstein@gmail.com'" , "'ludovic.desroches'" , "'linux-i2c@vger.kernel.org'" , 'Yanes Martinez Adrian' , "'linux-arm-kernel@lists.infradead.org'" , "'rmallon@gmail.com'" List-Id: linux-i2c@vger.kernel.org Le 08/27/2012 03:32 PM, Voss, Nikolaus a =E9crit : > Hi Adian, > > Yanes Martinez Adrian wrote on Monday, August 27, 2012 2:46 PM: >> Le 08/27/2012 12:40 PM, Yanes Martinez Adrian a =E9crit : >>> Hi Ludovic, >>> >>>> Tested on at91rm9200, at91sam9261, at91sam9g20 and at91sam9m10 with >>>> eeprom, temperature sensor and rtc devices (and wolfson chip for >>>> sam9g20). >>> >>> concerning the at91rm9200, what was the amount of bytes you >> transmitted? >>> >> >>> I have only checked that I can communicate with i2c devices so the >>> amount is very low (1-4 bytes). >> >> IIRC it was from >7 bytes when the issues appeared. >> >>> Some months ago I performed some testing[1] with the previous version of >>> the patch and the main conclusion was that the absence of PDC in the >>> AT91RM9200 made this driver unusable in such platform. > > I didn't get your last post in that thread. In my opinion RM9200 should = really > be excluded from being configured with this driver, what's your opinion > Ludovic? > After investigation, the transmission issue may concern rm9200, 9261, = 9260 and 9263. The main cause of this issue is we do not have clock = stretching. Using a low clock frequency should reduce the underrun issue so this = driver can be used on those chips but a warning have to be added to = indicate this potential issue. I'll do it when I'll resend patches for = DT support. Regards Ludovic > Regards, > Niko > > -- > To unsubscribe from this list: send the line "unsubscribe linux-i2c" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > >