Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752861AbdDLLwF (ORCPT ); Wed, 12 Apr 2017 07:52:05 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:33384 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751106AbdDLLwC (ORCPT ); Wed, 12 Apr 2017 07:52:02 -0400 Date: Wed, 12 Apr 2017 19:51:42 +0800 From: Peter Chen To: Niranjan Dighe Cc: Peter.Chen@freescale.com, gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] chipidea: Fix issue in reconnecing gadget without insmod/rmmod Message-ID: <20170412115142.GA18380@b29397-desktop> References: <20170411151624.GA4703@scoobydoo> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170411151624.GA4703@scoobydoo> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3562 Lines: 100 On Tue, Apr 11, 2017 at 08:46:24PM +0530, Niranjan Dighe wrote: > Currently usb_gadget_connect() is called only through gadget > registration via composite_driver_probe(). As a result, after a > disconnection, if the role transitions to host and back to gadget, > the gadget is not recognized by the host anymore. > This is a typical scenario with an iAP device in the following > usecase - > conn iAP dev -> send roleswitch command -> roleswitch ourself > to gadget -> disconnect iAP device -> roleswitch back to host to > enumerate the device again -> reconnect device -> resend the > roleswitch command -> roleswitch ourself to gadget -> ISSUE. > > To workaround this, do the following - > > 1. Restart OTG FSM on SLi interrupt and on switching role to gadget > so that device transitions to B_IDLE state from B_PERIPHERAL state. > A transition from B_IDLE to B_PERIPHERAL is needed to enable > interrups and restore the correct state of the chipidea controller > so that communication with host is possible > > 2. usb_gadget_connect() after roleswitch to gadget so that > gadget->ops->pullup() is called and D+ line is asserted. This > causes host to "see" the device and enumeration can happen. > > Signed-off-by: Niranjan Dighe > --- > drivers/usb/chipidea/debug.c | 10 +++++++++- > drivers/usb/chipidea/udc.c | 3 +++ > 2 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c > index a4f7db2..66c1485 100644 > --- a/drivers/usb/chipidea/debug.c > +++ b/drivers/usb/chipidea/debug.c > @@ -16,7 +16,7 @@ > #include "udc.h" > #include "bits.h" > #include "otg.h" > - > +extern void ci_hdrc_otg_fsm_restart(struct ci_hdrc *); > /** > * ci_device_show: prints information about device capabilities and status > */ > @@ -325,6 +325,14 @@ static ssize_t ci_role_write(struct file *file, const char __user *ubuf, > ci_role_stop(ci); > ret = ci_role_start(ci, role); > enable_irq(ci->irq); > + > + /* REVISIT - Avoid repeated FSM restart*/ > + > + if (role == CI_ROLE_GADGET) { > + ci_hdrc_otg_fsm_restart(ci); > + usb_gadget_connect(&ci->gadget); > + } > + > pm_runtime_put_sync(ci->dev); > > return ret ? ret : count; > diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c > index a0accd5..1e3b827 100644 > --- a/drivers/usb/chipidea/udc.c > +++ b/drivers/usb/chipidea/udc.c > @@ -29,6 +29,8 @@ > #include "otg.h" > #include "otg_fsm.h" > > +extern void ci_hdrc_otg_fsm_restart(struct ci_hdrc *); > + > /* control endpoint description */ > static const struct usb_endpoint_descriptor > ctrl_endpt_out_desc = { > @@ -1881,6 +1883,7 @@ static irqreturn_t udc_irq(struct ci_hdrc *ci) > ci->driver->suspend(&ci->gadget); > usb_gadget_set_state(&ci->gadget, > USB_STATE_SUSPENDED); > + ci_hdrc_otg_fsm_restart(ci); > spin_lock(&ci->lock); > } > } > -- Hi Niranjan, When working with iAP device, there are two role-switch methods - Through OTG FSM, and using sysfs entries under /sys/bus/platform/devices/ci_hdrc.0/inputs but you may need to patch code to keep vbus always on for A-device, it is not compliance with OTG spec. - Using role interface under debugfs (I move it under sysfs for v4.12). But you need to patch the code and let the A-device switch back to host after iAP is disconnected. You don't need to use above two methods together, I suggest using the 2nd method since OTG FSM is hard to maintain due to no mandatory use case for it. -- Best Regards, Peter Chen