[Bug] ARM: mxs: STI: console can't wake up from freeze

[Stefan Wahren]

Hi Russell,

> Russell King - ARM Linux <linux at armlinux.org.uk> hat am 23. Oktober 2016 um
> 15:31 geschrieben:
> 
> 
> On Sun, Oct 23, 2016 at 11:19:26AM +0200, Stefan Wahren wrote:
> > Hi,
> > 
> > i'm faced with the issue that on i.MX28 the console is unable to wake up
> > from
> > freeze ( suspend to idle). I tested it with Linux 4.9-rc1, 4.8 and 3.18 (
> > cmdline has
> > no_console_suspend=1 ) and also with a i.MX23 with the same result. The
> > suspend
> > seems to work, but there is no reaction to the console after the freeze
> > except
> > an hung task warning after some time:
> 
> I bet if you remove "no_console_suspend" (it's not =1) then it'll work.

unfortunately not:

Setting: no_console_suspend not in cmdline, Debug UART wakeup source enabled

echo mem > /sys/power/state

Result: Able to wakeup via Debug UART
Expected result: Able to wakeup via Debug UART

---

Setting: no_console_suspend not in cmdline, Debug UART wakeup source enabled

echo freeze > /sys/power/state

Result: Unable to wakeup via Debug UART (no hung task warning)
Expected result: Able to wakeup via Debug UART

---

Setting: no_console_suspend in cmdline, Debug UART as wakeup source enabled

echo mem > /sys/power/state

Result: Able to wakeup via Debug UART
Expected result: Able to wakeup via Debug UART

---

Setting: no_console_suspend in cmdline, Debug UART as wake source enabled

echo freeze > /sys/power/state

Result: Unable to wakeup via Debug UART (hung task warning after some minutes)
Expected result: Able to wakeup Debug via UART

---

Setting: no_console_suspend in cmdline, Debug UART as wake source disabled

echo mem > /sys/power/state

Result: Able to wakeup via Debug UART
Expected result: Able to wakeup via Debug UART

---

Setting: no_console_suspend in cmdline, Debug UART as wake source disabled

echo freeze > /sys/power/state

Result: Unable to wakeup via UART (hung task warning after some minutes)
Expected result: Able to wakeup via Debug UART

---

Here some more relevant information about the setup:

The console is operating on Debug UART which is a ARM PL011. The following
kernel configs are set:

CONFIG_PM_SLEEP=y
CONFIG_SUSPEND=y
CONFIG_SUSPEND_FREEZER=y
CONFIG_PM=y