Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753896AbdDLMs0 (ORCPT ); Wed, 12 Apr 2017 08:48:26 -0400 Received: from mail-oi0-f68.google.com ([209.85.218.68]:34066 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751218AbdDLMsV (ORCPT ); Wed, 12 Apr 2017 08:48:21 -0400 MIME-Version: 1.0 In-Reply-To: <20170412115142.GA18380@b29397-desktop> References: <20170411151624.GA4703@scoobydoo> <20170412115142.GA18380@b29397-desktop> From: Niranjan Dighe Date: Wed, 12 Apr 2017 18:18:20 +0530 Message-ID: Subject: Re: [PATCH] chipidea: Fix issue in reconnecing gadget without insmod/rmmod To: Peter Chen Cc: Peter.Chen@freescale.com, Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4269 Lines: 114 On Wed, Apr 12, 2017 at 5:21 PM, Peter Chen wrote: > 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 Thank you Peter for your response. Yes, I will try to switch the role on disconnection of iAP device to Host. If I understand correctly I have to do something like this - ci_role_stop(ci); //Gadget role stop ret = ci_role_start(ci, role); //Host role start correct? Regards, Niranjan