linux-kernel - [PATCH 4.0 073/105] ARM: dts: am335x-boneblack: disable RTC-only sleep to avoid hardware damage

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Date:	Fri, 19 Jun 2015 13:36:03 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Matthijs van Duin <matthijsvanduin@...il.com>,
	Robert Nelson <robertcnelson@...il.com>,
	Tony Lindgren <tony@...mide.com>, Felipe Balbi <balbi@...com>,
	Johan Hovold <johan@...nel.org>
Subject: [PATCH 4.0 073/105] ARM: dts: am335x-boneblack: disable RTC-only sleep to avoid hardware damage

4.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Matthijs van Duin <matthijsvanduin@...il.com>

commit 7a6cb0abe1aa63334f3ded6d2b6c8eca80e72302 upstream.

Avoid entering "RTC-only mode" at poweroff. It is unsupported by most
versions of BeagleBone, and risks hardware damage.

The damaging configuration is having system-power-controller
without ti,pmic-shutdown-controller.

Reported-by: Matthijs van Duin <matthijsvanduin@...il.com>
Tested-by: Matthijs van Duin <matthijsvanduin@...il.com>
Signed-off-by: Robert Nelson <robertcnelson@...il.com>
Cc: Tony Lindgren <tony@...mide.com>
Cc: Felipe Balbi <balbi@...com>
Cc: Johan Hovold <johan@...nel.org>
[Matthijs van Duin: added explanatory comments]
Signed-off-by: Matthijs van Duin <matthijsvanduin@...il.com>
Fixes: http://bugs.elinux.org/issues/143
[tony@...mide.com: updated comments with the hardware breaking info]
Signed-off-by: Tony Lindgren <tony@...mide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm/boot/dts/am335x-bone-common.dtsi |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

--- a/arch/arm/boot/dts/am335x-bone-common.dtsi
+++ b/arch/arm/boot/dts/am335x-bone-common.dtsi
@@ -223,6 +223,25 @@
 /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
+	 *
+	 * 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.)
+	 */
+	ti,pmic-shutdown-controller;
+
 	regulators {
 		dcdc1_reg: regulator@0 {
 			regulator-name = "vdds_dpr";


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