Linux/AM3352: Power management issue

Angel Falcon

Expert 1160 points

Part Number: AM3352

Tool/software: Linux

Hello,

We have our own board design based on am3352 processor and we use kernel 4.4.19 from TI SDK 03.01.00.06

We want to use PM modes but we have some problems.

This is my configuration regarding PM

#
# Power management options
#
CONFIG_SUSPEND=y
CONFIG_SUSPEND_FREEZER=y
# CONFIG_SUSPEND_SKIP_SYNC is not set
# CONFIG_HIBERNATION is not set
CONFIG_PM_SLEEP=y
# CONFIG_PM_AUTOSLEEP is not set
# CONFIG_PM_WAKELOCKS is not set
CONFIG_PM=y
CONFIG_PM_DEBUG=y
# CONFIG_PM_ADVANCED_DEBUG is not set
CONFIG_PM_SLEEP_DEBUG=y
# CONFIG_APM_EMULATION is not set
CONFIG_PM_OPP=y
CONFIG_PM_CLK=y
# CONFIG_WQ_POWER_EFFICIENT_DEFAULT is not set
CONFIG_CPU_PM=y
CONFIG_ARCH_SUSPEND_POSSIBLE=y
CONFIG_ARM_CPU_SUSPEND=y
CONFIG_ARCH_HIBERNATION_POSSIBLE=y
CONFIG_NET=y
CONFIG_NET_INGRESS=y

I copied am335x-pm-firmware.elf file from SDK to the FS, and it is loaded when booting

[   13.424655] remoteproc0: wkup_m3 is available
[   13.429147] remoteproc0: Note: remoteproc is still under development and considered experimental.
[   13.492413] wkup_m3_ipc 44e11324.wkup_m3_ipc: could not get rproc handle
[   13.557627] remoteproc0: THE BINARY FORMAT IS NOT YET FINALIZED, and backward compatibility isn't yet guaranteed.
[   13.839549] remoteproc0: powering up wkup_m3
[   13.855070] remoteproc0: Booting fw image am335x-pm-firmware.elf, size 217148
[   13.862619] remoteproc0: remote processor wkup_m3 is now up
[   13.868329] wkup_m3_ipc 44e11324.wkup_m3_ipc: CM3 Firmware Version = 0x191

But when I try to check PM possible states it is empty

root@arm:~# cat /sys/power/state
root@arm:~#

Could you please help us?

If you need more information please ask me.

Best regards

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

please follow processors.wiki.ti.com/.../Linux_Core_Power_Management_User's_Guide_(v4.1)

0 Angel Falcon over 8 years ago in reply to Biser Gatchev-XID

Expert 1160 points

Hi,

Thank you for your help. I am able to go to standby mode.
Now I am trying to setup a gpio for wakeup, following instructions from this link

processors.wiki.ti.com/.../AM335x_Power_Management_Standby_User's_Guide

but I found this

mkdir -p /debugfs
mount -t debugfs debugfs /debugfs
cd /debugfs/omap_mux/board/
echo uart1_rxd.gpio0_14=0x27,rising > standby_gpio_pad_conf
-bash: standby_gpio_pad_conf: Permission denied

Checking with mount command it seems to have rw option enabled

debugfs on /debugfs type debugfs (rw,relatime)

Any Idea about this problem?
Best regards

0 Biser Gatchev-XID over 8 years ago in reply to Angel Falcon

TI__Guru**** 393215 points

This link is very old. You should refer to the wiki link I posted above.

0 Angel Falcon over 8 years ago in reply to Biser Gatchev-XID

Expert 1160 points

Yes, I check that link to configure PM, but It does not show how to use a GPIO to wake up from standby.

Where can I find this?

Best regards

0 Pavel Botev over 8 years ago in reply to Angel Falcon

TI__Guru**** 170625 points

Hi Angel,

I made some search and it seems that this standby_gpio_pad_conf feature is deprecated for linux kernel 3.12, 3.14 (and newer), it is valid for linux kernel 3.2 (TI SDK6). See the below e2e thread for more info:

e2e.ti.com/.../2013983

Regards,
Pavel

0 Michael Erdahl over 8 years ago in reply to Angel Falcon

TI__Genius 13505 points

Hi Angel,

To clear up a few things, first, AM335x only supports resuming from low-power modes (standby and suspend) in GPIO bank 0. GPIO banks 1-3 do not support the low-power wakeup feature.

To configure a GPIO pin as a wake up source, the best way is to setup a gpio-key instance in your device tree. This will associated your GPIO pin with wake up capability and an interrupt.

Take a look at the "gpio_keys: volume_keys@0" node in the am335x-evm.dts device tree as a reference. Let's assume you will use GPIO0_31 as an example - your device tree should contain entries like this:

@am33xx_pinmux {
  pinctrl-names = "default";
  pinctrl-0 = < ... &test_keys>;

  ...

  test_keys: test_keys {
    0x74 (PIN_INPUT_PULLDOWN | MUX_MODE7);  /* gpmc_wpn.gpio0_31 */
  };

  ...

  keys: test_keys@0 {
    compatible = "gpio-keys";
    #address-cells = <1>;
    #size-cells = <0>;
    autorepeat;

    test@0 {
      label = "J4-pin21";
      linux,code = <155>;
      gpios = <&gpio0 31 GPIO_ACTIVE_LOW>;
      gpio-key,wakeup;
    };
  };

  ...
};

One thing to note- I just key code 155 at random- you will want to choose something here that makes sense for your application and does not collide with anything else.

Regards,
Mike

0 Angel Falcon over 8 years ago in reply to Michael Erdahl

Expert 1160 points

Hi Mike,

Thanks a lot for your response

Best regards
Angel

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Linux/AM3352: Power management issue