Re: [PATCH] ARM: dts: am335x-bone* enable pmic-shutdown-controller

On Wed, May 13, 2015 at 04:16:58PM +0200, Johan Hovold wrote:

On Wed, May 13, 2015 at 08:50:01AM -0500, Robert Nelson wrote:

quoted

Fixes: http://bugs.elinux.org/issues/143

Commit 672e2b147 which introduced proper shutdown chose to let the PMIC go into sleep-state (aka "RTC-only mode") rather than off-state. This was fine for rev A5 on which that patch was tested, but since then two changes have been made to the power supply scheme:

(rev A6) enable of the 3v3b regulator moved from LDO2 to LDO4 (3v3a)
side-effect: 3v3b rail remains on in sleep-mode (also in off-mode when battery-powered)

(rev A6A) am335x vdds supply moved from LDO3 to LDO1
side-effect: vdds remains supplied in sleep-mode

As a result heavy leakage occurs from vdds (directly) and 3v3b (via i/o pins) to the 3v3a. The amount of current depends on external connections, but for example leaving a serial console cable connected in this state resulted in serious violation of am335x absolute maximum ratings, with potential for hardware damage.

Reported-by: Matthijs van Duin <redacted>
Tested-by: Matthijs van Duin <redacted>
Signed-off-by: Robert Nelson <redacted>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Felipe Balbi <redacted>
Cc: Johan Hovold <johan@kernel.org>

This should go into stable as well:

Fixes: 672e2b147413 ("ARM: dts: am335x-boneblack: enable power off and
rtc wake up")
Cc: stable <redacted>	# 3.19
Acked-by: Johan Hovold <johan@kernel.org>

By the way, perhaps you should add a comment in the tps node explaining
why ti,pmic-shutdown-controller must not be disabled (on what revisions
of hardware) as well?

Johan