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Mon, 5 Mar 2018 03:50:00 -0500 Received: from mga05.intel.com ([192.55.52.43]:12726 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932892AbeCEIuA (ORCPT ); Mon, 5 Mar 2018 03:50:00 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,426,1515484800"; d="asc'?scan'208";a="205543538" From: Felipe Balbi To: Roger Quadros Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] usb: dwc3: Prevent indefinite sleep in _dwc3_set_mode during suspend/resume In-Reply-To: <94cd6377-1327-2309-8d69-6ab0de2bdfd4@ti.com> References: <1519730526-22274-1-git-send-email-rogerq@ti.com> <87sh9l5z4l.fsf@linux.intel.com> <94cd6377-1327-2309-8d69-6ab0de2bdfd4@ti.com> Date: Mon, 05 Mar 2018 10:49:00 +0200 Message-ID: <87po4i3o1v.fsf@linux.intel.com> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" 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: --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Hi, Roger Quadros writes: >> Roger Quadros writes: >>> In the following test we get stuck by sleeping forever in _dwc3_set_mod= e() >>> 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) >>>=20=20 >>> void dwc3_gadget_exit(struct dwc3 *dwc) >>> { >>> + int epnum; >>> + unsigned long flags; >>> + >>> + spin_lock_irqsave(&dwc->lock, flags); >>> + for (epnum =3D 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) { >>> + struct dwc3_ep *dep =3D dwc->eps[epnum]; >>> + >>> + if (!dep) >>> + continue; >>> + >>> + dep->flags &=3D ~DWC3_EP_END_TRANSFER_PENDING; >>> + } >>> + spin_unlock_irqrestore(&dwc->lock, flags); >>> + >>> usb_del_gadget_udc(&dwc->gadget); >>> dwc3_gadget_free_endpoints(dwc); >>=20 >> 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. >>=20 > > 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. =2D-=20 balbi --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEElLzh7wn96CXwjh2IzL64meEamQYFAlqdBHwACgkQzL64meEa mQbe8BAApM8ROUSrH/D3DTIV4VXCPJhFv+0N8KKQaO6iz1DIko2ptR7t+AXBakTi ZBoZBlqNlc7WAiyhTTgvC57meUz+6QX+PaeuvvbmGld7a2H6/6hTPwpkS6lY4oR+ HPEB1RY2w1ZgboBKs2G82r1agNbgTg9FdssX2eplJbjwoRpHlVYQHP9BEWZ1nu5q kDEcdUFdAX9BpLUaakOQfm5zuuWAeAok4evPz0gpwn16eJEfwLqgePXjUmZEO9zK H8JUUouamr/aXfIUZcAzpOPl810g2WOFlcD9icjI+nL2N6Mpnx23iKk4hKC6u5ep nlgC0AAzM0IyHYsVjzNq/Q0fOy02nTm2yVgkrof6lk4/DvEXdnMij1diK74gH+CK IAJ5TLDNntACZ6DQgqJf8gwvkM1evTgG2esHJVQgQjozxbJFeP1woErajq4VZ2jg ybyKw7Oyap59Z1ZZIGSEHmTFCrwo++jLxM82hWtRlypBUosvDuuX5NgxV6AIZ9tl PDL6erLyBpy3aA3qT5wTh/+eD1Eq5fRJpLpZwBjubctfIts1/WepOglrLen44sEU CnxlC5xsslbd/Dg74UdY40YC3cbNKrWVqzbmdl7rTV7hW34gN2Yc5cpM8BWsrgnj ymlT8waELwLi3WhrLFhOlugk5MueJTzJplyaJlcX6qqH1RDiHzc= =6U7u -----END PGP SIGNATURE----- --=-=-=--