From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932969AbcIBQmv (ORCPT ); Fri, 2 Sep 2016 12:42:51 -0400 Received: from mail.pqgruber.com ([178.189.19.235]:45810 "EHLO mail.pqgruber.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932236AbcIBQmt (ORCPT ); Fri, 2 Sep 2016 12:42:49 -0400 Date: Fri, 2 Sep 2016 18:42:43 +0200 From: Clemens Gruber To: Peter Chen Cc: linux-usb@vger.kernel.org, Greg Kroah-Hartman , linux-kernel@vger.kernel.org Subject: Re: chipidea: udc: kernel panic in isr_setup_status_phase Message-ID: <20160902164243.GA4549@archie.localdomain> References: <20160823003630.GA3052@archie.localdomain> <20160824081102.GA27233@shlinux2> <20160825234740.GA12850@archie.localdomain> <20160826172151.GA21360@b29397-desktop> <20160828181502.GA7785@archie.localdomain> <20160829102402.GA3736@b29397-desktop> <20160830172045.GA2634@archie.localdomain> <20160902015552.GE11262@shlinux2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160902015552.GE11262@shlinux2> User-Agent: Mutt/1.7.0 (2016-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 02, 2016 at 09:55:52AM +0800, Peter Chen wrote: > Do you have other 5V to USB_H1_VBUS? USB PHY needs 5V input voltage > as the source for USB LDO (3.0v), either from OTG or Host 1. I suspect > the lower vbus voltage causes the USB LDO voltage less than 3.0v, then > cause the unstable for USB PHY. If possible, you can connect MAIN 5V > (if it exists) directly to USB_H1_VBUS to see if this problem is fixed. Yes, USB_H1_VBUS is supplied from internal 5V and it is accurate (+/- 0.03V). The USB_H_EN signal enables USB_H1_VBUS through a MIC2026-1. The USB_OTG_VBUS signal from the picture with 4.69V came from the host PC and is not under our control. I read in the ReferenceManual that the USBPHY defaults to USB_H1_VBUS if both USB_OTG_VBUS and USB_H1_VBUS are available. If we imagine the following situation: USB OTG cable is plugged-in, the board is powered on, USB_OTG_VBUS is supplied externally and USBPHY uses it because USB_H1_EN is not high yet and did not enable USB_H1_VBUS. If the USBPHY started out being supplied by USB_OTG_VBUS and later on, USB_H1_VBUS comes up, will the USBPHY switch to USB_H1_VBUS immediately or stay at being supplied by USB_OTG_VBUS as long as that is available? > Great. Can you see the sudden lower for vbus again? If it still exists, it may > be GND issue. Yes it is still visible. Does not seem to be a problem though. > Avoid NULL pointer deference is necessary. Patch is welcome :) Yes, but should we also stop the gadget driver and print an error message? Or just return from the isr and neither report nor stop? Regards, Clemens