From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-ob0-f177.google.com ([209.85.214.177]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1SBRfn-0004g3-GC for barebox@lists.infradead.org; Sat, 24 Mar 2012 14:10:27 +0000 Received: by obbup16 with SMTP id up16so4102228obb.36 for ; Sat, 24 Mar 2012 07:10:25 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: Date: Sat, 24 Mar 2012 15:10:25 +0100 Message-ID: From: Martin Fuzzey List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: barebox-bounces@lists.infradead.org Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: i.MX21 USB OTG To: Derald Woods Cc: barebox@lists.infradead.org Hi Derald, On Fri, Mar 23, 2012 at 2:09 PM, Derald Woods wrote: > Hello Martin, > > I have an existing design that uses the i.MX21 ARM9 processor. The > design currently uses an external USB OTG chip. The chip is now > end-of-life. I know that this is an older ARM processor. It still meets > most of the design needs. Is the i.MX21 OTG functionality considered > reliable? I have not seen any real success stories with the i.MX21 USB > OTG implementation. Our board currently utilizes the USB OTG chip at > the bootloader and Linux kernel level. > It depends what you mean by OTG. The i.MX21 silicon has 3 USB ports, two of which can only be used as USB hosts and one which is configurable as host only, function (device) only or OTG (dynamic switching). Somewhat confusingly the Freescale documentation refers to the whole module as "USB-OTG". However the mainline code only supports host mode (there is no function driver nor OTG support) I mainlined the i.MX21 HCD driver for 2.6.34 and fixed a few bugs for 2.6.37 (in particular problems with non aligned buffers causing usbnet to fail). Since then I haven't had any bug reports, the driver also passes the USB test suite (which I updated to check the buffer alignment behaviour). > I would appreciate being pointed in the right direction or warned of > impending danger. Basically I want to know if the mx21 USB OTG has > performed well for other embedded Linux designs. > Something very close to the original code on which I based the driver was shipped with the Chumby (which uses a heavily patched 2.6.16 kernel). However that code had quite a few bugs and didn't support isochronous transfers at all. I don't have any direct feedback myself of real world use of the driver however since we ended up not shipping an iMX21 based Linux product for non technical reasons. > I had originally posted to the Barebox mailing list. > Ah I'm not subscribed to that list - adding it as a CC hoping it's not subscriber only Cheers, Martin Fuzzey _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox