> -----Original Message----- > From: Alexandre Belloni [mailto:alexandre.bell...@free-electrons.com] > Sent: Tuesday, April 19, 2016 12:22 AM > To: Qianyu Gong <qianyu.g...@nxp.com> > Cc: akinobu.m...@gmail.com; Mingkai Hu <mingkai...@nxp.com>; rtc- > li...@googlegroups.com; linux-kernel@vger.kernel.org > Subject: Re: rtc ds3232 call trace in kernel > > On 18/04/2016 at 06:15:40 +0000, Qianyu Gong wrote : > > 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. > > > > 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. > > > > > > Well, many RTC drivers actually suffer from that. I'm planning to change the > infrastructure to handle this case better. > Meanwhile, this is worth fixing. > > > -- > Alexandre Belloni, Free Electrons > Embedded Linux, Kernel and Android engineering http://free-electrons.com
Thanks. I followed Akinobu's suggest and put devm_rtc_device_register() just before registering the irq handler. The call trace disappeared. Looks like it's working well. Regards, Qianyu
