ARM: dts: am335x-boneblack: disable RTC-only sleep

Here's a version that attempts to address Tony's earlier request to
include some comments in the patch itself. Since I saw no way to
concisely summarize the issues, I included links to relevant messages
(and enough info to locate the thread again in case of link rot).

Since the patch itself contains more explanation, I made the commit
message more concise.

Apologies for the attachment (inline text would get fucked up by gmail)

* Matthijs van Duin <matthijsvanduin@gmail.com> [150531 22:16]:
> Here's a version that attempts to address Tony's earlier request to
> include some comments in the patch itself. Since I saw no way to
> concisely summarize the issues, I included links to relevant messages
> (and enough info to locate the thread again in case of link rot).

Ah finally you got around doing a proper patch :)
 
> Since the patch itself contains more explanation, I made the commit
> message more concise.
> 
> Apologies for the attachment (inline text would get fucked up by gmail)

Hmm no ideas about that, I guess people are using gmail to send email
with smtps though?

> From 4278ecc32e886d2e83bc486e6409d8f6df82a0d1 Mon Sep 17 00:00:00 2001
> From: Matthijs van Duin <matthijsvanduin@gmail.com>
> Date: Mon, 1 Jun 2015 06:56:24 +0200
> Subject: [PATCH] ARM: dts: am335x-bone* enable pmic-shutdown-controller
> 
> Fixes: http://bugs.elinux.org/issues/143
> 
> Avoid entering "RTC-only mode" at poweroff. It is unsupported by most
> versions of BeagleBone, and risks hardware damage.
> 
> Reported-by: Matthijs van Duin <matthijsvanduin@gmail.com>
> Tested-by: Matthijs van Duin <matthijsvanduin@gmail.com>
> Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Felipe Balbi <balbi@ti.com>
> Cc: Johan Hovold <johan@kernel.org>
> [Matthijs van Duin: added explanatory comments]
> Signed-off-by: Matthijs van Duin <matthijsvanduin@gmail.com>
> ---
>  arch/arm/boot/dts/am335x-bone-common.dtsi | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/am335x-bone-common.dtsi b/arch/arm/boot/dts/am335x-bone-common.dtsi
> index c3255e0..90fbbb1 100644
> --- a/arch/arm/boot/dts/am335x-bone-common.dtsi
> +++ b/arch/arm/boot/dts/am335x-bone-common.dtsi
> @@ -223,6 +223,24 @@
>  /include/ "tps65217.dtsi"
>  
>  &tps {
> +	// Configure pmic to enter OFF-state instead of SLEEP-state ("RTC-only
> +	// mode") at poweroff.  Most BeagleBone versions do not support RTC-only
> +	// mode and risk hardware damage if this mode is entered.
> +	//
> +	// For details, see linux-omap mailing list May 2015 thread
> +	//	[PATCH] ARM: dts: am335x-bone* enable pmic-shutdown-controller
> +	// In particular, messages:
> +	//	http://www.spinics.net/lists/linux-omap/msg118585.html
> +	//	http://www.spinics.net/lists/linux-omap/msg118615.html
> +	//
> +	ti,pmic-shutdown-controller;
> +	//
> +	// You can override this later with
> +	//	&tps {  /delete-property/ ti,pmic-shutdown-controller;  }
> +	// if you want to use RTC-only mode and made sure you are not affected
> +	// by the hardware problems. (Tip: double-check by performing a current
> +	// measurement after shutdown: it should be less than 1 mA.)
> +
>  	regulators {
>  		dcdc1_reg: regulator@0 {
>  			regulator-name = "vdds_dpr";

Linux usually does not use the // style comments.. Can you please change
that? And how about have just one section of comments then the entry
for ti,pmic-shutdown-controller? Or maybe something like this:

	/*
	 * Configure pmic to enter OFF-state instead of SLEEP-state ("RTC-only
	 * mode") at poweroff.  Most BeagleBone versions do not support RTC-only
	 * ....
	 */
	&tps {
		ti,pmic-shutdown-controller;

		regulators {
			...
		};
		...
	};

Also, if this is needed as a fix for the mainline kernel to avoid hardware
damage, please let me know too ASAP.

Regards,

Tony
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* Matthijs van Duin <matthijsvanduin@gmail.com> [150601 12:35]:
> On 1 June 2015 at 19:23, Tony Lindgren <tony@atomide.com> wrote:
> > Ah finally you got around doing a proper patch :)
> 
> My First Linux Patch(tm) ;-)

Probably easier than trying to get other people to do the right
thing by writing emails ;)
 
> > Also, if this is needed as a fix for the mainline kernel to avoid hardware
> > damage, please let me know too ASAP.
> 
> The damaging configuration is having &rtc { system-power-controller; }
> without &tps { ti,pmic-shutdown-controller; }

OK thanks updating the description with that.
 
> So 3d76be5b9 also avoids damage, but with the unfortunate side-effect
> that the system doesn't power off at all anymore (it just halts). I do
> recommend applying this patch (restyled as needed) before reverting
> 3d76be5b9.
> 
> > Hmm no ideas about that, I guess people are using gmail to send email
> > with smtps though?
> 
> Hmm, setting up mutt turned out less hassle than I remembered...
> 
> (Let's hope all goes well)
> 
> > Linux usually does not use the // style comments.. Can you please change
> > that? And how about have just one section of comments then the entry
> > for ti,pmic-shutdown-controller?
> 
> Fresh try...

Thanks applying into omap-for-v4.1/fixes with Cc stable.

Regards,

Tony
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* Johan Hovold <johan@kernel.org> [150611 07:20]:
> This reverts commit 3d76be5b933e2a66d85a2f7444e68e99e8a48ad4.
> 
> The latest revision of Beaglebone Black does not support RTC-only mode.
> 
> To avoid potential hardware damage, RTC-only mode was disabled by
> default by commit 7a6cb0abe1aa ("ARM: dts: am335x-boneblack: disable
> RTC-only sleep to avoid hardware damage").
> 
> Unfortunately, an incorrect fix had already been applied, which instead
> of just disabling RTC-only mode, prevents the Beaglebone from powering
> down at all.
> 
> Revert this patch to fix the power-off regression.
> 
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
> 
> The offending patch was incorrectly applied after Matthijs initial fix
> was posted and before the final fix (which only added some comments) was
> applied.
> 
> Note that the final version of the fix 7a6cb0abe1aa ("ARM: dts:
> am335x-boneblack: disable RTC-only sleep to avoid hardware damage")
> indicates that it should be backported to 3.12 even though RTC-only mode
> was first enabled in 3.19.

Applying this now into omap-for-v4.2/fixes.

Regards,

Tony
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