From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) by yocto-www.yoctoproject.org (Postfix) with ESMTP id 2CB2EE003D3 for ; Tue, 13 Aug 2013 11:30:07 -0700 (PDT) Received: by mail-pa0-f54.google.com with SMTP id kx10so3714631pab.13 for ; Tue, 13 Aug 2013 11:30:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type :content-transfer-encoding; bh=t+DnYyS1SHoXBfZwa76+CDyq5EGJYwjUpcnnsIqrj4M=; b=PEjZ2tfEjA3+GXJFjebYiRjmICXspowE0PjzkPLinKpBClAi/XO/gEd4Vn4gSzAv5y 5mujg6AOwTQss3yypvn1t1XSIm2ugSbvKMsXHzOpcHClGmnpuDqBOlszYWxeomPDAWxc Q+h9377hnpPRoBhGEgFIUI+SoSRY8r667e9MumGG9ICTcqo0BONsSHON8VkBoxufmLdN WTjtwBFAyc4ugmEQJgIz73eWJbvdfIDBM9R5OYVLnv9qKbTq6QWTy7jfyrvltn9gs+g0 bnqPHOLToRaFa6HmGsNrWTzRBmXLVafgqcIrgb8im+d91IIjPo39HlQfBsFnxWgBs2+g UI4g== X-Gm-Message-State: ALoCoQk2gGHat2BeD87v3K0wgwJwqicbwbCJeZo/3lpWK19/AhjrgE5yoB9zleoVP8Wto/nhw/84 X-Received: by 10.66.194.13 with SMTP id hs13mr4273926pac.163.1376418607478; Tue, 13 Aug 2013 11:30:07 -0700 (PDT) Received: from [192.168.0.15] ([70.96.116.236]) by mx.google.com with ESMTPSA id vz4sm11774626pab.11.2013.08.13.11.30.04 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 13 Aug 2013 11:30:06 -0700 (PDT) Message-ID: <520A7B28.3000604@boundarydevices.com> Date: Tue, 13 Aug 2013 11:30:00 -0700 From: Eric Nelson User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: Thanassis Silis References: In-Reply-To: Cc: "meta-freescale@yoctoproject.org" Subject: Re: speed of /dev/i2c-2 in imx6q sabre-lite X-BeenThere: meta-freescale@yoctoproject.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Usage and development list for the meta-fsl-* layers List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Aug 2013 18:30:12 -0000 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Thanassis, On 08/13/2013 11:03 AM, Thanassis Silis wrote: > Hello everyone, > I am unaware as to who sets clock speed on the i2c bus and specifically > on the /dev/i2c-2 which is exposed on the board so as to drive external > equipment. > > I am looking into the linux-boundary kernel files in yocto (dylan) build > dir, but I cannot figure out where that is set. > To be honest I don't even know if i'll find that info there, but it > seems like the right place to start (after googling about it of course). > > So who determined the speed (standard mode, fast mode, etc) for the > external i2c? if it is a driver , which one should I be looking for? > This structure defines the speed of the I2C bus: https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_3.0.35_4.0.0/arch/arm/mach-mx6/board-mx6_nitrogen6x.c#L434 To change it for i2c-2 by itself, you'll need to make a copy of that, change the speed value and pass the copy to the routine imx6q_add_imx_i2c(): https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_3.0.35_4.0.0/arch/arm/mach-mx6/board-mx6_nitrogen6x.c#L1320 > The reason is I am trying to drive some TMC222 low-power stepper motor > control ICs, but they do not respond. > Note I have successfully connected a number of other i2c ICs (among > others the pca9505x). > > An answer is not necessary. Any pointers as to how to go about it , so I > can learn about this is more than welcome. > Thank you for your help. > This should be straightforward. Let me know if you have any trouble. Regards, Eric