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spf=none smtp.mailfrom=linux-usb-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=ti.com header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=fail (body has been altered; 1024-bit rsa key sha256) header.d=ti.com header.i=@ti.com header.b=zNrMjHfd x-bits=1024 x-keytype=rsa x-algorithm=sha256 x-selector=ti-com-17Q1; dmarc=fail (p=quarantine,has-list-id=yes,d=quarantine) header.from=ti.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-usb-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=ti.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933463AbeCELOc (ORCPT ); Mon, 5 Mar 2018 06:14:32 -0500 Received: from fllnx209.ext.ti.com ([198.47.19.16]:64266 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933116AbeCELOa (ORCPT ); Mon, 5 Mar 2018 06:14:30 -0500 Subject: Re: [PATCH] usb: dwc3: Prevent indefinite sleep in _dwc3_set_mode during suspend/resume To: Felipe Balbi , Baolin Wang CC: USB , LKML References: <1519730526-22274-1-git-send-email-rogerq@ti.com> <87sh9l5z4l.fsf@linux.intel.com> <94cd6377-1327-2309-8d69-6ab0de2bdfd4@ti.com> <87po4i3o1v.fsf@linux.intel.com> <87k1uq3ho6.fsf@linux.intel.com> From: Roger Quadros Message-ID: <8ec0485e-89af-568b-e34a-b0cd490817d0@ti.com> Date: Mon, 5 Mar 2018 13:14:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <87k1uq3ho6.fsf@linux.intel.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-GB Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-usb-owner@vger.kernel.org X-Mailing-List: linux-usb@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 05/03/18 13:06, Felipe Balbi wrote: > > Hi, > > Baolin Wang writes: >>>> Roger Quadros writes: >>>>>> Roger Quadros writes: >>>>>>> In the following test we get stuck by sleeping forever in _dwc3_set_mode() >>>>>>> after which dual-role switching doesn't work. >>>>>>> >>>>>>> On dra7-evm's dual-role port, >>>>>>> - Load g_zero gadget driver and enumerate to host >>>>>>> - suspend to mem >>>>>>> - disconnect USB cable to host and connect otg cable with Pen drive in it. >>>>>>> - resume system >>>>>>> - we sleep indefinitely in _dwc3_set_mode due to. >>>>>>> dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()-> >>>>>>> dwc3_gadget_stop()->wait_event_lock_irq() >>>>>>> >>>>>>> Let's clear the DWC3_EP_END_TRANSFER_PENDING flag on all endpoints >>>>>>> so we don't wait in dwc3_gadget_stop(). >>>>>>> >>>>>>> Signed-off-by: Roger Quadros >>>>>>> --- >>>>>>> drivers/usb/dwc3/gadget.c | 14 ++++++++++++++ >>>>>>> 1 file changed, 14 insertions(+) >>>>>>> >>>>>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c >>>>>>> index 2bda4eb..0a360da 100644 >>>>>>> --- a/drivers/usb/dwc3/gadget.c >>>>>>> +++ b/drivers/usb/dwc3/gadget.c >>>>>>> @@ -3273,6 +3273,20 @@ int dwc3_gadget_init(struct dwc3 *dwc) >>>>>>> >>>>>>> void dwc3_gadget_exit(struct dwc3 *dwc) >>>>>>> { >>>>>>> + int epnum; >>>>>>> + unsigned long flags; >>>>>>> + >>>>>>> + spin_lock_irqsave(&dwc->lock, flags); >>>>>>> + for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) { >>>>>>> + struct dwc3_ep *dep = dwc->eps[epnum]; >>>>>>> + >>>>>>> + if (!dep) >>>>>>> + continue; >>>>>>> + >>>>>>> + dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING; >>>>>>> + } >>>>>>> + spin_unlock_irqrestore(&dwc->lock, flags); >>>>>>> + >>>>>>> usb_del_gadget_udc(&dwc->gadget); >>>>>>> dwc3_gadget_free_endpoints(dwc); >>>>>> >>>>>> free endpoints is a better place for this. It's already going to free >>>>>> the memory anyway. Might as well clear all flags to 0 there. >>>>>> >>>>> >>>>> But it won't solve the deadlock issue. Since dwc3_gadget_free_endpoints() >>>>> is called after usb_del_gadget_udc() and the deadlock happens when >>>>> >>>>> usb_del_gadget_udc()->udc_stop()->dwc3_gadget_stop()->wait_event_lock_irq() >>>>> >>>>> and DWC3_EP_END_TRANSFER_PENDING flag is set. >>>> >>>> indeed. Iterating twice over the entire endpoint list seems >>>> wasteful. Perhaps we just shouldn't wait when removing the UDC since >>>> that's essentially what this patch will do, right? If you clear the flag >>>> before calling ->udc_stop(), this means the loop in dwc3_gadget_stop() >>>> will do nothing. Might as well remove it. >>>> >>> >>> This means that we will never wait for DWC3_EP_END_TRANSFER_PENDING to clear >>> in dwc3_gadget_stop() like we used to. This is perfectly fine, right? >>> >>> It makes sense to me as dwc3_gadget_stop() calls __dwc3_gadget_stop() which >>> masks all interrupts and nobody will ever clear that flag if it was set. >> >> I don't think so. It can not mask the endpoint events, please check >> the events which will be masked in DEVTEN register. The reason why we >> should wait for DWC3_EP_END_TRANSFER_PENDING to clear is that, >> sometimes the DWC3_DEPEVT_EPCMDCMPLT event will be triggered later >> than 100us, but now we may have freed the gadget irq which will cause >> crash. > > We could mask command complete events as soon as ->udc_stop() is called, > right? Hmm, actually, __dwc3_gadget_stop() already clears DEVTEN > completely. But which bit in DEVTEN says Endpoint events are disabled? > > /me goes check databook > > At least on revision 2.60a of the databook, bit 10 is reserved. I wonder > if that's the start of all the problems. Anybody has access to older and > newer databook revisions so we can cross-check? > I can access v2.40 and v3.10 books. bit 10 is reserved on both Differences in v2.4 vs v3.10 are: bit 8 reserved vs L1SUSPEN bit 13 reserved vs StopOnDisconnectEn bit 14 reserved vs L1WKUPEVTEN -- cheers, -roger Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki