From mboxrd@z Thu Jan 1 00:00:00 1970 From: ludovic.desroches Subject: Re: [PATCH] i2c: at91: add of_device_id entry for at91rm9200 Date: Thu, 24 Jan 2013 10:09:22 +0100 Message-ID: <5100FA42.7050905@atmel.com> References: <1354743732-11581-1-git-send-email-manabian@gmail.com> <20121218060232.GL23971@game.jcrosoft.org> <20130124072714.GH8364@nekote.pengutronix.de> <5100E9A4.9020804@atmel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit 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: Joachim Eastwood Cc: nicolas.ferre@atmel.com, Wolfram Sang , "ludovic.desroches" , linux-i2c@vger.kernel.org, Jean-Christophe PLAGNIOL-VILLARD , linux-arm-kernel@lists.infradead.org List-Id: linux-i2c@vger.kernel.org On 01/24/2013 09:43 AM, Joachim Eastwood wrote: > On 24 January 2013 08:58, ludovic.desroches wrote: >> Hi, >> >> >> On 01/24/2013 08:27 AM, Wolfram Sang wrote: >>> >>> On Tue, Dec 18, 2012 at 07:02:32AM +0100, Jean-Christophe PLAGNIOL-VILLARD >>> wrote: >>>> >>>> On 22:42 Wed 05 Dec , Joachim Eastwood wrote: >>>>> >>>>> Signed-off-by: Joachim Eastwood >>>>> --- >>>>> Hi, >>>>> >>>>> AT91RM9200 is gaining DT support now so let's add an id to the i2c >>>>> driver. >>>>> >>>>> Tested on custom RM9200 board. Since the driver doesn't support pinctrl >>>>> muxing yet I had to add pinctrl hogs for the i2c pins in my dts for it >>>>> to work. >>>> >>>> >>>> IIRC the i2c IP have quite a lots of issue on rm9200 and until sam9g45 >>>> >>>> it not recommended to use it instead use i2c-gpio >>> >>> >>> Ludovic, you know the driver best. Does it make sense to add this? >> >> >> I didn't add this when I did the rework because there was no DT tree support >> for RM9200. The configuration for RM9200 IP is already in the driver and >> used for non DT platform so I think it makes sense to add this. >> >> But as Jean-Christophe said, it's recommended to use the i2c-gpio driver >> since we know the first versions of the IP have several issues. However if >> it fits user usage, it is not forbidden to use it. > > I assumed the new driver handles the HW quirks better than the old atmel-twi > driver(?). So the RM9200 i2c HW is at least usable with this driver. > No it doesn't handle HW quirks (clock stretching, stop command, etc.) better for old IP versions than the old atmel-twi. Since we have no workarounds for these quirks, it was recommended to use i2c-gpio. > I didn't encounter any problems during my short testing using a couple of > different i2c devices. As far as I can remember the old driver didn't even > handle the devices I tested with the new driver. I also did some tests on RM9200 with basic i2c devices and everything go well so yes it is usable that's why I think this patch can be applied. Regards Ludovic