switching to kernel/i2c list, see below for details.
Jocke
-----Original Message-----
From: Kumar Gala [mailto:[email protected]]
Sent: 17 November 2006 17:57
To: Joakim Tjernlund
Cc: [email protected]
Subject: Re: RTC , ds1307 I2C driver and NTP does not work.
On Nov 17, 2006, at 10:38 AM, Joakim Tjernlund wrote:
> I get this when I activathte NTP and ntp "sync" the time the I2C HW
> clock.
You may be better off posting this to lkml and copy the i2c list (and
rtc if one exists). Since its more a driver issue than anything
really ppc specific. Clearly we are doing schedules() in mpc_xfer()
and maybe we shouldn't be.
- kumar
> BUG: scheduling while atomic: swapper/0x00010000/0
> Call Trace:^M
> [C0245C80] [C000860C] show_stack+0x48/0x194 (unreliable)
> [C0245CB0] [C01BEFF4] schedule+0x5d4/0x618
> [C0245CF0] [C01BF9C8] schedule_timeout+0x70/0xd0
> [C0245D30] [C014416C] i2c_wait+0x164/0x1d8
> [C0245D80] [C0144490] mpc_xfer+0x2b0/0x3a8
> [C0245DD0] [C01423E8] i2c_transfer+0x58/0x7c
> [C0245DF0] [C0141124] ds1307_set_time+0x1bc/0x234
> [C0245E00] [C013F82C] rtc_set_time+0xb0/0xb8^M
> [C0245E20] [C000BFC4] set_rtc_class_time+0x34/0x58
> [C0245E40] [C000C8D0] timer_interrupt+0x5a0/0x5fc
> [C0245EE0] [C000F7B0] ret_from_except+0x0/0x14
> --- Exception: 901 at cpu_idle+0xc8/0xf0
> LR = cpu_idle+0xec/0xf0
> [C0245FC0] [C000388C] rest_init+0x28/0x38
> [C0245FD0] [C01F36E0] start_kernel+0x1d8/0x228
> [C0245FF0] [00003438] 0x3438
>
> I have activated RTC CLASS and have this in my board file:
> #ifdef CONFIG_RTC_CLASS
> late_initcall(rtc_class_hookup);
> #endif
>
> kernel 2.6.19-rc5
>
> Jocke
>
> _______________________________________________
> Linuxppc-dev mailing list
> [email protected]
> https://ozlabs.org/mailman/listinfo/linuxppc-dev
> -----Original Message-----
> From:
> Sent: 17 November 2006 17:57
> To: Joakim Tjernlund
> Cc: [email protected]
> Subject: Re: RTC , ds1307 I2C driver and NTP does not work.
>
>
> On Nov 17, 2006, at 10:38 AM, Joakim Tjernlund wrote:
>
>> I get this when I activathte NTP and ntp "sync" the time the I2C HW
>> clock.
>
> You may be better off posting this to lkml and copy the i2c list (and
> rtc if one exists). Since its more a driver issue than anything
> really ppc specific. Clearly we are doing schedules() in mpc_xfer()
> and maybe we shouldn't be.
>
> - kumar
Please try this patch:
<http://permalink.gmane.org/gmane.linux.kernel/467686>
Message-ID: <[email protected]>
____
On Fri, 17 Nov 2006 18:38:10 +0100, Joakim Tjernlund wrote:
> On Nov 17, 2006, at 10:38 AM, Joakim Tjernlund wrote:
>
> > I get this when I activathte NTP and ntp "sync" the time the I2C HW
> > clock.
>
> You may be better off posting this to lkml and copy the i2c list (and
> rtc if one exists). Since its more a driver issue than anything
> really ppc specific. Clearly we are doing schedules() in mpc_xfer()
> and maybe we shouldn't be.
It's OK to schedule or sleep in mpc_xfer. It's not OK to call mpc_xfer
from an interrupt context, which is what appears to be happening here.
So the ds1307 driver would need to be changed not to directly call
i2c_transfer from the interrupt. Using a workqueue should work.
That being said, I wonder why one would want to set the time from an
interrupt context in the first place. Maybe that's what needs fixing.
> > BUG: scheduling while atomic: swapper/0x00010000/0
> > Call Trace:^M
> > [C0245C80] [C000860C] show_stack+0x48/0x194 (unreliable)
> > [C0245CB0] [C01BEFF4] schedule+0x5d4/0x618
> > [C0245CF0] [C01BF9C8] schedule_timeout+0x70/0xd0
> > [C0245D30] [C014416C] i2c_wait+0x164/0x1d8
> > [C0245D80] [C0144490] mpc_xfer+0x2b0/0x3a8
> > [C0245DD0] [C01423E8] i2c_transfer+0x58/0x7c
> > [C0245DF0] [C0141124] ds1307_set_time+0x1bc/0x234
> > [C0245E00] [C013F82C] rtc_set_time+0xb0/0xb8^M
> > [C0245E20] [C000BFC4] set_rtc_class_time+0x34/0x58
> > [C0245E40] [C000C8D0] timer_interrupt+0x5a0/0x5fc
> > [C0245EE0] [C000F7B0] ret_from_except+0x0/0x14
> > --- Exception: 901 at cpu_idle+0xc8/0xf0
> > LR = cpu_idle+0xec/0xf0
> > [C0245FC0] [C000388C] rest_init+0x28/0x38
> > [C0245FD0] [C01F36E0] start_kernel+0x1d8/0x228
> > [C0245FF0] [00003438] 0x3438
> >
> > I have activated RTC CLASS and have this in my board file:
> > #ifdef CONFIG_RTC_CLASS
> > late_initcall(rtc_class_hookup);
> > #endif
> >
> > kernel 2.6.19-rc5
> >
> > Jocke
--
Jean Delvare
>
> On Fri, 17 Nov 2006 18:38:10 +0100, Joakim Tjernlund wrote:
> > On Nov 17, 2006, at 10:38 AM, Joakim Tjernlund wrote:
> >
> > > I get this when I activathte NTP and ntp "sync" the time
> the I2C HW
> > > clock.
> >
> > You may be better off posting this to lkml and copy the i2c
> list (and
> > rtc if one exists). Since its more a driver issue than anything
> > really ppc specific. Clearly we are doing schedules() in
> mpc_xfer()
> > and maybe we shouldn't be.
>
> It's OK to schedule or sleep in mpc_xfer. It's not OK to call mpc_xfer
> from an interrupt context, which is what appears to be happening here.
> So the ds1307 driver would need to be changed not to directly call
> i2c_transfer from the interrupt. Using a workqueue should work.
>
> That being said, I wonder why one would want to set the time from an
> interrupt context in the first place. Maybe that's what needs fixing.
That's the way kernel NTP code always has done it. Probably to minimize latency, ideally
you want to set the time when a new second occur since that's what most RTC HW expects.
Will a workqueue run directly after the one return from IRQ context?
>
> > > BUG: scheduling while atomic: swapper/0x00010000/0
> > > Call Trace:^M
> > > [C0245C80] [C000860C] show_stack+0x48/0x194 (unreliable)
> > > [C0245CB0] [C01BEFF4] schedule+0x5d4/0x618
> > > [C0245CF0] [C01BF9C8] schedule_timeout+0x70/0xd0
> > > [C0245D30] [C014416C] i2c_wait+0x164/0x1d8
> > > [C0245D80] [C0144490] mpc_xfer+0x2b0/0x3a8
> > > [C0245DD0] [C01423E8] i2c_transfer+0x58/0x7c
> > > [C0245DF0] [C0141124] ds1307_set_time+0x1bc/0x234
> > > [C0245E00] [C013F82C] rtc_set_time+0xb0/0xb8^M
> > > [C0245E20] [C000BFC4] set_rtc_class_time+0x34/0x58
> > > [C0245E40] [C000C8D0] timer_interrupt+0x5a0/0x5fc
> > > [C0245EE0] [C000F7B0] ret_from_except+0x0/0x14
> > > --- Exception: 901 at cpu_idle+0xc8/0xf0
> > > LR = cpu_idle+0xec/0xf0
> > > [C0245FC0] [C000388C] rest_init+0x28/0x38
> > > [C0245FD0] [C01F36E0] start_kernel+0x1d8/0x228
> > > [C0245FF0] [00003438] 0x3438
> > >
> > > I have activated RTC CLASS and have this in my board file:
> > > #ifdef CONFIG_RTC_CLASS
> > > late_initcall(rtc_class_hookup);
> > > #endif
> > >
> > > kernel 2.6.19-rc5
> > >
> > > Jocke
>
> --
> Jean Delvare
>
>
Hi Joakim,
On Sat, 18 Nov 2006 15:51:09 +0100, Joakim Tjernlund wrote:
> > It's OK to schedule or sleep in mpc_xfer. It's not OK to call mpc_xfer
> > from an interrupt context, which is what appears to be happening here.
> > So the ds1307 driver would need to be changed not to directly call
> > i2c_transfer from the interrupt. Using a workqueue should work.
> >
> > That being said, I wonder why one would want to set the time from an
> > interrupt context in the first place. Maybe that's what needs fixing.
>
> That's the way kernel NTP code always has done it. Probably to minimize
> latency, ideally you want to set the time when a new second occur since
> that's what most RTC HW expects.
>
> Will a workqueue run directly after the one return from IRQ context?
There is no guarantee as to when the workqueue will process the request
as far as I know. The actual delay probably depends on the value of HZ.
There is no way around the delay in the case of I2C RTC chips anyway
(at least not with the current implementation), as the underlying I2C
bus driver may sleep as part of the bus transaction, and the RTC chip
driver can virtually be attached to every bus.
Note that the transaction itself will take some time anyway, I2C can be
quite slow.
--
Jean Delvare