From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-iy0-f177.google.com ([209.85.210.177]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1SBTdC-00055d-Nv for barebox@lists.infradead.org; Sat, 24 Mar 2012 16:15:55 +0000 Received: by iaky10 with SMTP id y10so7461099iak.36 for ; Sat, 24 Mar 2012 09:15:53 -0700 (PDT) Date: Sat, 24 Mar 2012 11:15:39 -0500 From: "Derald D. Woods" Message-ID: <20120324161538.GA15950@exodus> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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: Martin Fuzzey Cc: barebox@lists.infradead.org On Sat, Mar 24, 2012 at 03:10:25PM +0100, Martin Fuzzey wrote: > 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 Hello Martin, Thanks for the detailed feedback. This information is consistent with what I have observed and followed with regard to the i.MX21. It will help us chart a meaningful development course. Best regards, Derald D. Woods _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox