Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752589AbcJMIAp (ORCPT ); Thu, 13 Oct 2016 04:00:45 -0400 Received: from mail-yb0-f169.google.com ([209.85.213.169]:33748 "EHLO mail-yb0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752215AbcJMIAf (ORCPT ); Thu, 13 Oct 2016 04:00:35 -0400 MIME-Version: 1.0 In-Reply-To: <87inswvg80.fsf@linux.intel.com> References: <87r37kviic.fsf@linux.intel.com> <87inswvg80.fsf@linux.intel.com> From: Baolin Wang Date: Thu, 13 Oct 2016 16:00:34 +0800 Message-ID: Subject: Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq To: Felipe Balbi Cc: 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: 2433 Lines: 70 Hi, On 13 October 2016 at 15:51, Felipe Balbi wrote: > > Hi, > > Baolin Wang writes: >> Hi, >> >> On 13 October 2016 at 15:02, Felipe Balbi wrote: >>> >>> Hi, >>> >>> Baolin Wang writes: >>>> @@ -1742,6 +1791,17 @@ static int dwc3_gadget_stop(struct usb_gadget *g) >>>> dwc->gadget_driver = NULL; >>>> spin_unlock_irqrestore(&dwc->lock, flags); >>>> >>>> + /* >>>> + * Since the xHCI will share the same interrupt with gadget, thus when >>>> + * free the gadget irq, it will not shutdown this gadget irq line. Then >>>> + * the gadget driver can not handle the end transfer command complete >>>> + * event after free the gadget irq, which will hang the system to crash. >>>> + * >>>> + * So we should wait for the end transfer command complete event before >>>> + * free it to avoid this situation. >>>> + */ >>>> + dwc3_wait_command_complete(dwc); >>> >>> this doesn't make sense. We have already masked all interrupts before >>> getting here. We have also, already, disabled all endpoints. >> >> No, you just mask the interrupts described in DEVTEN register, and you >> did not disable the endpoint command complete event. > > True that > >>> I'm thinking this is a bug in configfs interface of Gadget API, not >>> dwc3. The only reason for this to happen would be if we get to >>> ->udc_stop() with endpoints still enabled. >>> >>> Can you check if that's the case? i.e. can you check if any endpoints >>> are still enabled when we get here? >> >> No, it is not any endpoints are still enabled. Like I said in commit >> message, we will start end transfer command when disable the endpoint, >> if the end transfer command complete event comes after we have freed >> the gadget irq, it will trigger the interrupt line all the time to >> crash the system. > > I see what the problem is. Databook tells us we *must* set CMDIOC when > issuing EndTransfer command and we should always wait for Command > Complete IRQ. However, we took a shortcut and just delayed for 100us > after issuing End Transfer. Yes, but 100us delay is not enough in some scenarios, like changing function with configfs frequently, we will met problems. > > It seems as if *that* should be fixed. We should start actually waiting > for Command Complete IRQ. > > -- > balbi -- Baolin.wang Best Regards