Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754041AbcLMVPT (ORCPT ); Tue, 13 Dec 2016 16:15:19 -0500 Received: from mail-oi0-f41.google.com ([209.85.218.41]:33756 "EHLO mail-oi0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754011AbcLMVPQ (ORCPT ); Tue, 13 Dec 2016 16:15:16 -0500 MIME-Version: 1.0 In-Reply-To: References: <1481612990-23409-1-git-send-email-john.stultz@linaro.org> <1481612990-23409-3-git-send-email-john.stultz@linaro.org> From: John Stultz Date: Tue, 13 Dec 2016 12:40:15 -0800 Message-ID: Subject: Re: [RFC][PATCH 2/5] usb: dwc2: Workaround case where GOTGCTL state is wrong To: Vardan Mikayelyan Cc: lkml , Wei Xu , Guodong Xu , Amit Pundir , Rob Herring , John Youn , Douglas Anderson , Chen Yu , Kishon Vijay Abraham I , Felipe Balbi , Greg Kroah-Hartman , "linux-usb@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: 2878 Lines: 71 On Tue, Dec 13, 2016 at 4:28 AM, Vardan Mikayelyan wrote: > On 12/13/2016 11:12 AM, John Stultz wrote: >> When removing a USB-A to USB-otg adapter cable, we get a change >> status irq, and then in dwc2_conn_id_status_change, we >> erroniously see the GOTGCTL_CONID_B flag set. This causes us to >> get stuck in the "while (!dwc2_is_device_mode(hsotg))" loop, >> spitting out "Waiting for Peripheral Mode, Mode=Host" warnings >> until it fails out many seconds later. >> >> This patch works around the issue by re-reading the GOTGCTL >> state to check if the GOTGCTL_CONID_B is still set and if not >> restarting the change status logic. >> >> I suspect this isn't the best solution, but it seems to work >> well for me. >> >> Feedback would be greatly appreciated! >> >> Cc: Wei Xu >> Cc: Guodong Xu >> Cc: Amit Pundir >> Cc: Rob Herring >> Cc: John Youn >> Cc: Douglas Anderson >> Cc: Chen Yu >> Cc: Kishon Vijay Abraham I >> Cc: Felipe Balbi >> Cc: Greg Kroah-Hartman >> Cc: linux-usb@vger.kernel.org >> Acked-by: John Youn >> Signed-off-by: John Stultz >> --- >> drivers/usb/dwc2/hcd.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c >> index df5a065..a3f34dd 100644 >> --- a/drivers/usb/dwc2/hcd.c >> +++ b/drivers/usb/dwc2/hcd.c >> @@ -3199,7 +3199,7 @@ static void dwc2_conn_id_status_change(struct work_struct *work) >> dev_dbg(hsotg->dev, "gotgctl=%0x\n", gotgctl); >> dev_dbg(hsotg->dev, "gotgctl.b.conidsts=%d\n", >> !!(gotgctl & GOTGCTL_CONID_B)); >> - >> +again: >> /* B-Device connector (Device Mode) */ >> if (gotgctl & GOTGCTL_CONID_B) { >> /* Wait for switch to device mode */ >> @@ -3210,6 +3210,9 @@ static void dwc2_conn_id_status_change(struct work_struct *work) >> dwc2_is_host_mode(hsotg) ? "Host" : >> "Peripheral"); >> usleep_range(20000, 40000); >> + gotgctl = dwc2_readl(hsotg->regs + GOTGCTL); >> + if (!(gotgctl & GOTGCTL_CONID_B)) >> + goto again; >> if (++count > 250) >> break; >> } >> > Hi John Stultz, > > When it goes to ":again", it will go to else anyways. I'll suggest > alternative way to do this. Please see below. Sounds good. I've made the change. > Also you can add "Reviewed-by: Vardan Mikayelyan " Thanks so much for your review! -john