[Letux-kernel] power management problems in ehci-omap

Tony Lindgren tony at atomide.com
Tue Feb 6 19:16:23 CET 2018

* Andreas Kemnade <andreas at kemnade.info> [180206 18:04]:
> On Tue, 6 Feb 2018 09:17:37 -0800
> Tony Lindgren <tony at atomide.com> wrote:
> > uarts=$(find /sys/class/tty/tty[SO]*/power/ -type d 2>/dev/null)
> > for uart in $uarts; do
> > 	echo enabled > $uart/wakeup 2>&1
> > 	echo auto > $uart/control 2>&1
> > done
> > 
> hmm, this looks a bit like runtime suspend.

Not only that, it enables wakeup for UART also for suspend :)

That is if your dts has it configured with interrupts-extended
for the console UART like omap3-beagle-xm.dts has for example.
Seems like the gta04 dts don't have these.. And you also want
to have chosen with stdout-path = &uart3 or whatever the debug
UART is for earlycon to work.

> I mean suspend aka echo mem >/sys/power/state
> > echo -n 1 > /sys/kernel/debug/pm_debug/enable_off_mode

And the above will enable SoC and PMIC off modes, which will also
take the suspend power to some much much lower value :) You need
to configure the PMIC too depending if the oscillator can be turned
off, in that case set "ti,twl4030-power-idle-osc-off". That too
seems to be missing in gta04 dts files..



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