Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753983AbcJMKlR (ORCPT ); Thu, 13 Oct 2016 06:41:17 -0400 Received: from mail-yb0-f169.google.com ([209.85.213.169]:35154 "EHLO mail-yb0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752859AbcJMKlP (ORCPT ); Thu, 13 Oct 2016 06:41:15 -0400 MIME-Version: 1.0 In-Reply-To: <87d1j4vasr.fsf@linux.intel.com> References: <521625dd7f5e335e2a681ec65ebffc5832207e5f.1475570367.git.baolin.wang@linaro.org> <87oa2ovicc.fsf@linux.intel.com> <87d1j4vasr.fsf@linux.intel.com> From: Baolin Wang Date: Thu, 13 Oct 2016 18:41:14 +0800 Message-ID: Subject: Re: [RESEND PATCH v3 1/2] usb: dwc3: gadget: Add disconnect checking when changing function dynamically To: Felipe Balbi Cc: Janusz Dziedzic , Greg KH , Mark Brown , USB , LKML 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: 2308 Lines: 65 On 13 October 2016 at 17:49, Felipe Balbi wrote: > > Hi, > > Baolin Wang writes: >>>>>>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c >>>>>>>> index 1783406..ca2ae5b 100644 >>>>>>>> --- a/drivers/usb/dwc3/gadget.c >>>>>>>> +++ b/drivers/usb/dwc3/gadget.c >>>>>>>> @@ -241,6 +241,9 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned cmd, >>>>>>>> int susphy = false; >>>>>>>> int ret = -EINVAL; >>>>>>>> >>>>>>>> + if (!dwc->pullups_connected) >>>>>>>> + return -ESHUTDOWN; >>>>>>>> + >>>>> >>>>> you skip trace_dwc3_gadget_ep_cmd() >>>> >>>> Yes, we did not need trace here since we did not send out the command. >>>> >>> What in such case: enumeration will not work and this will be because >>> this ESHUTDOWN or wrong pullups_connected usage. Without a trace you >>> will not know where the problem is. >>> In my opinion this trace could be useful. >> >> We have returned the '-ESHUTDOWN' error number for user to know what >> happened. > > No, this is actually not good and Janusz has a very valid point > here. When we're debugging something in dwc3, we want to rely on > tracepoints to tell us what's going on. I don't want to have to add more > debugging messages to print out that ESHUTDOWN error just so I can > figure out what's going on. You should be patching this in a way that > the tracepoint is still printed out properly. Fine. Will fix this in next version. > > Keep in mind that you should be setting ret to -ESHUTDOWN and make sure > the trace is printed. Same patch should, then, patch trace.h to handle > -ESHUTDOWN as an error case, i.e. following hunk should be added: > > diff --git a/drivers/usb/dwc3/debug.h b/drivers/usb/dwc3/debug.h > index d93780e84f07..70b783f0507d 100644 > --- a/drivers/usb/dwc3/debug.h > +++ b/drivers/usb/dwc3/debug.h > @@ -319,6 +319,8 @@ static inline const char *dwc3_ep_cmd_status_string(int status) > switch (status) { > case -ETIMEDOUT: > return "Timed Out"; > + case -ESHUTDOWN: > + return "Shut Down"; > case 0: > return "Successful"; > case DEPEVT_TRANSFER_NO_RESOURCE: > > -- > balbi -- Baolin.wang Best Regards