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

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Date:	Mon, 27 Oct 2014 16:22:51 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Johan Hovold <johan@...nel.org>
Cc:	Felipe Balbi <balbi@...com>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Tony Lindgren <tony@...mide.com>,
	Benoît Cousson <bcousson@...libre.com>,
	Lokesh Vutla <lokeshvutla@...com>,
	Guenter Roeck <linux@...ck-us.net>, nsekhar@...com,
	t-kristo@...com, j-keerthy@...com, linux-omap@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org,
	Russell King <rmk+kernel@....linux.org.uk>
Subject: Re: [PATCH v2 00/20] rtc: omap: fixes and power-off feature

On Fri, 24 Oct 2014 21:55:32 +0200 Johan Hovold <johan@...nel.org> wrote:

> On Fri, Oct 24, 2014 at 02:44:42PM -0500, Felipe Balbi wrote:
> > On Fri, Oct 24, 2014 at 09:36:55PM +0200, Johan Hovold wrote:
> > > On Fri, Oct 24, 2014 at 02:29:48PM -0500, Felipe Balbi wrote:
> > > > Hi,
> > > > 
> > > > On Fri, Oct 24, 2014 at 02:25:40PM -0500, Felipe Balbi wrote:
> 
> > > > > 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.
> > > 
> > > That's expected (see below). It works with v3.18-rc1 vanilla because
> > > machine_halt is called instead of machine_power_off as there is no
> > > registered power-off handler.
> > 
> > yeah, that much I figured :-)
> > 
> > > > ok, so it seems like it takes more than 1 second for things to
> > > > propagate. If I increase that mdelay() to 3000, then everything works
> > > > fine on my end. I think we should get RMK's input on this 3000ms delay
> > > > to machine_power_off(). Should it be generic, or should we add it to our
> > > > rtc pm_power_off implementation ?
> > > 
> > > As I wrote above, we still need a 2-second mdelay in rtc-omap, which I
> > > intend to add to the pmic_power_en patch.
> > 
> > oh, alright then. If you can Cc me, I'll make sure to test that too ;-)
> 
> I will. :) Just wanted to see whether Andrew preferred I resend the
> whole series or just that one patch first.
> 
> The diff is minimal:
> 
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index e74750f00b18..e4f97ad9eb21 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -423,6 +423,8 @@ static void omap_rtc_power_off(void)
>         val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
>         rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
>                         val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
> +
> +       mdelay(2000);
>  }

Yes, having read this threadlet: we need a very good comment in there
explaining what's going on, please.

Do we even need this delay on anything other than arm?  Or even on all arm?
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