[PATCH 3.14 36/44] ARM: dts: am335x-boneblack: disable RTC-only sleep to avoid hardware damage

Greg Kroah-Hartman
2015-06-19T21:00:31Z

From: Matthijs van Duin <matthijsvanduin@gmail.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@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>
Fixes: http://bugs.elinux.org/issues/143
[tony@atomide.com: updated comments with the hardware breaking info]
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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
@@ -226,6 +226,25 @@
/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-always-on;