Re: [PATCH v2 00/20] rtc: omap: fixes and power-off feature

[Felipe Balbi]

On Fri, Oct 24, 2014 at 09:02:51PM +0200, Johan Hovold wrote:
> [ +CC: Russell ]
> 
> On Fri, Oct 24, 2014 at 11:08:45AM -0500, Felipe Balbi wrote:
> 
> > I tested this entire series with my BBB and it still works fine. However
> > I still get below panic. This time without any DRM errors:
> > 
> > [   63.087832] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000
> > [   63.087832] 
> > [   63.097399] CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 3.18.0-rc1-00095-g8524e69 #556
> > [   63.106060] [<c00175a4>] (unwind_backtrace) from [<c00132f0>] (show_stack+0x20/0x24)
> > [   63.114160] [<c00132f0>] (show_stack) from [<c0657404>] (dump_stack+0x8c/0xa4)
> > [   63.121706] [<c0657404>] (dump_stack) from [<c0654f70>] (panic+0xa0/0x220)
> > [   63.128895] [<c0654f70>] (panic) from [<c0049e64>] (do_exit+0x974/0x9d0)
> > [   63.135900] [<c0049e64>] (do_exit) from [<c006775c>] (SyS_reboot+0x14c/0x1e8)
> > [   63.143361] [<c006775c>] (SyS_reboot) from [<c000f080>] (ret_fast_syscall+0x0/0x48)
> > [   63.151596] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000
> > 
> > Then again, this also happens by simply calling poweroff without
> > enabling wakealarm.
> 
> Bah, I forgot to look into that. I haven't seen this myself as I don't
> use systemd (which does the syscall from process 0).
> 
> Some driver power-off implementations and some arch machine_power_off
> spin indefinitely (or use an mdelay and WARN) after trying to power off.
> 
> I think this is really a bug in arch/arm that should be fixed
> analogously to how failed reboot is handled in machine_restart().
> 
> Care to try the patch below?
> 
> I should still add a two-second delay to rtc-omap to avoid the arch
> error message.
> 
> Andrew, can you update one patch in the series or should I just resend
> them all (with proper Tested-by tags)?
> 
> > In any case, for the whole series:
> > 
> > Tested-by: Felipe Balbi <balbi@xxxxxx>
> 
> Thanks for testing!
> 
> Johan
> 
> 
> >From aaa1d1d6171c895b6966ba5b738ac7946ada97c7 Mon Sep 17 00:00:00 2001
> From: Johan Hovold <johan@xxxxxxxxxx>
> Date: Fri, 24 Oct 2014 18:53:09 +0200
> Subject: [PATCH] ARM: fix failed power-off handling
> 
> Make sure to handle failed power off by printing an error message and
> halting (analogously to how failed reboot is handled).
> 
> Power off can fail for example if the hardware has not been wired up
> correctly.
> 
> This avoids a kernel panic when called from process 0:
> 
> [   63.087832] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000
> [   63.087832]
> [   63.097399] CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 3.18.0-rc1-00095-g8524e69 #556
> [   63.106060] [<c00175a4>] (unwind_backtrace) from [<c00132f0>] (show_stack+0x20/0x24)
> [   63.114160] [<c00132f0>] (show_stack) from [<c0657404>] (dump_stack+0x8c/0xa4)
> [   63.121706] [<c0657404>] (dump_stack) from [<c0654f70>] (panic+0xa0/0x220)
> [   63.128895] [<c0654f70>] (panic) from [<c0049e64>] (do_exit+0x974/0x9d0)
> [   63.135900] [<c0049e64>] (do_exit) from [<c006775c>] (SyS_reboot+0x14c/0x1e8)
> [   63.143361] [<c006775c>] (SyS_reboot) from [<c000f080>] (ret_fast_syscall+0x0/0x48)
> [   63.151596] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000
> 
> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
> ---
>  arch/arm/kernel/process.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
> index a35f6ebbd2c2..68c38af5687c 100644
> --- a/arch/arm/kernel/process.c
> +++ b/arch/arm/kernel/process.c
> @@ -212,6 +212,12 @@ void machine_power_off(void)
>  
>  	if (pm_power_off)
>  		pm_power_off();
> +
> +	/* Give a grace period for failure to power off */
> +	mdelay(1000);
> +
> +	pr_err("Power off failed -- system halted\n");
> +	while (1);
>  }

with this I always get to "Power off failed -- system halted". If I
switch to v3.18-rc1 vanilla, then it works. So it's definitely caused by
your rtc-only patches.

-- 
balbi

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