> -----Original Message----- > From: Akinobu Mita [mailto:akinobu.m...@gmail.com] > Sent: Tuesday, April 19, 2016 11:58 AM > To: Qianyu Gong <qianyu.g...@nxp.com> > Cc: alexandre.bell...@free-electrons.com; Mingkai Hu <mingkai...@nxp.com>; > rtc-li...@googlegroups.com; linux-kernel@vger.kernel.org > Subject: Re: rtc ds3232 call trace in kernel > > 2016-04-19 11:36 GMT+09:00 Qianyu Gong <qianyu.g...@nxp.com>: > > > >> -----Original Message----- > >> From: Akinobu Mita [mailto:akinobu.m...@gmail.com] > >> Sent: Monday, April 18, 2016 9:02 PM > >> To: Qianyu Gong <qianyu.g...@nxp.com> > >> Cc: alexandre.bell...@free-electrons.com; Mingkai Hu > >> <mingkai...@nxp.com>; rtc-li...@googlegroups.com; > >> linux-kernel@vger.kernel.org > >> Subject: Re: rtc ds3232 call trace in kernel > >> > >> 2016-04-18 15:15 GMT+09:00 Qianyu Gong <qianyu.g...@nxp.com>: > >> > Hi Akinobu, > >> > > >> > > >> > > >> > I got an rtc call trace when booting 4.6 kernel on our board and I > >> > found it > >> > > >> > was caused by this patch: > >> > > >> > > >> > > >> > commit fc1dcb0b39dbb10d3290f2fcd6e154670f699166 > >> > > >> > Author: Akinobu Mita <akinobu.m...@gmail.com> > >> > > >> > Date: Mon Mar 7 00:27:53 2016 +0900 > >> > > >> > > >> > > >> > rtc: ds3232: use rtc->ops_lock to protect alarm operations > >> > > >> > > >> > > >> > ds3232->mutex is used to protect for alarm operations which > >> > > >> > need to access status and control registers. > >> > > >> > > >> > > >> > But we can use rtc->ops_lock instead. rtc->ops_lock is held > >> > when most > >> > > >> > of rtc_class_ops methods are called, so we only need to > >> > explicitly > >> > > >> > acquire it from irq handler in order to protect form concurrent > >> > > >> > accesses. > >> > > >> > > >> > > >> > Signed-off-by: Akinobu Mita <akinobu.m...@gmail.com> > >> > > >> > Signed-off-by: Alexandre Belloni > >> > <alexandre.bell...@free-electrons.com > >> > > >> > > >> > > >> > The problem is that rtc->ops_lock would be accessed in ds3232_irq() > >> > > >> > without being initialized as rtc_device_register() is called too late. > >> > >> You have already identified the root cause of this issue. > >> > >> > As I’m not familiar with rtc things, could I just revert the patch > >> > or you already > >> > > >> > have a solution to this problem? Thanks in advance. > >> > >> Could you check if the problem is resolved by moving the call of > >> devm_rtc_device_register() from the end of ds3232_probe() to just > >> before registering irq handler? > > > > Yes. It works(no call trace now). > > Thanks for testing. Do you mind submitting your patch to rtc- > li...@googlegroups.com ?
No problem.:) Regards, Qianyu
