From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: OMAP3430: MUSB host and hot-plugging Date: Thu, 20 Mar 2008 12:30:03 -0700 Message-ID: <200803201230.03729.david-b@pacbell.net> References: <87d4pqqmj2.fsf@paris.hilman.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from smtp120.sbc.mail.sp1.yahoo.com ([69.147.64.93]:40051 "HELO smtp120.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753772AbYCTTaJ (ORCPT ); Thu, 20 Mar 2008 15:30:09 -0400 In-Reply-To: <87d4pqqmj2.fsf@paris.hilman.org> Content-Disposition: inline Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Kevin Hilman Cc: linux-omap@vger.kernel.org On Wednesday 19 March 2008, Kevin Hilman wrote: > However, if I then plug the key back in, nothing happens. > > Forcing a session start via "echo 'F' > /proc/driver/musb_hdrc" causes > the device to be (re)detected and things look good again. It is not > until I force the session start that I see the interrupt and the > CONNECT event. > > Any ideas why this isn't detected on insertion? Just for the record ... that's always been a problem. There's some strange side-effect driven magic in the Mentor IP, right in that area, which has always been fragile. For example, it seems to think something other than the state of the ID pin should control whether it's in the A-side state machine (default host) or the B-side one (default peripheral), and it gets fairly twitchey about VBUS levels too ... as in, it doesn't allow the specified 100 msec for it to stabilize, and enters a fault/shutdown mode if voltage drops because of, say, contact bounce or inrush current, while it stabilizes. Needing that "force session start" is a warning flag. The very notion of that kind of "session" is something introduced by Mentor, which is not part of the OTG spec (at least, not in anything like that form). Multiple weeks have been wasted trying to sort out misbehavior in that area, and there seem to be revision-specific issues too. - Dave