• State Resolved
  • Locked Locked
  • Replies 13 replies
  • Subscribers 98 subscribers
  • Views 2159 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

suspend - power management

ranchu
Guru 20755 points

Hello,

Is suspend routine called automatically when the kernel moves to IDLE  or is it only triggered by userspace explicit call ? 

Thanks,

Ran

  • 0
    TI__Guru** 116100 points

    Hi Ran,

    In power management perspective, we have 2 types of suspend mode, one is "suspend" and second on is "run time suspend" mode.

    "run time suspend" mode function will call automatically when the device doesn't received any interrupts or simple it is IDLE.

    "suspend" mode would initiated by the "/sys/power/state" SYSFS entry.

  • 0 in reply to Titusrathinaraj Stalin
    Guru 20755 points

    Hi Titus,

    Thanks for the quick response.

    I now see that the run time suspend is what described in Documentation\omap\runtime_pm.txt as:
    int pm_generic_runtime_suspend(struct device *dev);    

    As to the use of /sys/devices/.../power/autosuspend_delay_ms attribute , is there alternative for sysfs ? We disabled sysfs in our kernel.

    Thanks,

    Ran

  • 0 in reply to ranchu
    TI__Guru** 116100 points

    Hi Ran,

    I don't think that it won't be any problem since it have default 'ms' delay, you need SYSFS support if you want to change from default.

  • 0 in reply to Titusrathinaraj Stalin
    Guru 20755 points

    Hi Titus,

    Where can I find example or documentation to runtime suspend ?
    The documentation in power\runtime_pm.txt is not relevant for OMAP PM, right ?
    Can you point me to more information on runtime suspend/resume ?

     

    Thanks!

    Ran

  • 0 in reply to ranchu
    TI__Guru** 116100 points

    Hi Ran,

    The documentation in power\runtime_pm.txt is not relevant for OMAP PM, right ?


    No, It is generic linux power management.

    You can implement "runtime power management" for your linux driver through ".runtime_suspend" and ".runtime_resume" APIs.

    You have to use ".pm" member in driver's fops to use runtime power management.

    Refer any driver from linux.

    drivers/usb/core/usb.c

    Ex: USB

    static const struct dev_pm_ops usb_device_pm_ops = {
	.prepare =	usb_dev_prepare,
	.complete =	usb_dev_complete,
	.suspend =	usb_dev_suspend,
	.resume =	usb_dev_resume,
	.freeze =	usb_dev_freeze,
	.thaw =		usb_dev_thaw,
	.poweroff =	usb_dev_poweroff,
	.restore =	usb_dev_restore,
#ifdef CONFIG_USB_SUSPEND
	.runtime_suspend =	usb_runtime_suspend,
	.runtime_resume =	usb_runtime_resume,
	.runtime_idle =		usb_runtime_idle,
#endif
};


struct device_type usb_device_type = {
	.name =		"usb_device",
	.release =	usb_release_dev,
	.uevent =	usb_dev_uevent,
	.devnode = 	usb_devnode,
#ifdef CONFIG_PM
	.pm =		&usb_device_pm_ops,
#endif
};

     

  • 0 in reply to Titusrathinaraj Stalin
    Guru 20755 points

    Hi Titus,

    I didn't understand, Isn't ".runtime_suspend" relevant only to the generic PM ?
    The above example for usb is also relevant when used with OMAP PM ?

    Thanks!

    Ran

  • 0 in reply to ranchu
    TI__Guru** 116100 points

    Hi Ran,

    Yes, it is also applicable for OMAP PM.

  • 0 in reply to Titusrathinaraj Stalin
    Guru 20755 points

    Hi Titus,

    Thanks very much.

    The above example is applicable for platform device. Is there any example for character device ?

    Thanks,

    Ran

  • 0 in reply to ranchu
    TI__Guru** 116100 points

    Hi Ran,

    Actually, what is your requirement ?

    So that, I can suggest you to proceed with good method.

  • 0 in reply to Titusrathinaraj Stalin
    Guru 20755 points

    Hi Titus,

    Thank you very much for the suggestion, It is most helpful.

    My requirements are as following:
    1. wakeup at any interrupt whatsoever such as: SW timers, gpio etc.
    2. all suspend/resume are at runtime (automatic) as part of the standby mode. It also requires run time suspend of some character drivers such as dsp (using external dsp through character device)
    3. there is no sysfs,debugfs in system so the initialization of the PM drivers should be done in other method. (There is probably no need for change afterwards anything,  because the inetntion is that everything is automatic)

    If there is also some code example of this issue for OMAP PM, such as more exact example of suspend runtime used in OMAP PM, it will be helpful.
    Thank a lot,
    Ran

  • 0 in reply to ranchu
    TI__Guru** 116100 points

    Hi Ran,

    if you want to proceed with runtime suspend/resume method then you must to use platform driver which supports runtime PM but not character device.

    You must to put your PM code stuffs in runtime platform fops function, ie platform driver would hook the runtime power management code at runtime (device_put and device_get).

    If any driver which supports ".pm" member on their fops structure (any platform driver : say ex MMC/USB etc.,) then that driver can be used '.suspend' and '.runtime_suspend' fns.

    Please refer to the linux doc.

    Documentation/power/runtime_pm.txt

  • 0 in reply to Titusrathinaraj Stalin
    Guru 20755 points

    Hi Titus,

    Isn't Documentation/power/runtime_pm.txt relevant only for the generic PM and not for OMAP PM ?
    Another thing, do you think It is a good method to create dummy platform driver for the suspend/resume, which communicates with another character device (for example external dsp) ?

    Thanks,

    Ran

  • 0 in reply to Titusrathinaraj Stalin
    Guru 20755 points

    Hi Titus,

    Do you mean that the runtime suspend/resume is part of the generic linux PM, while suspend/resume (non-runtime) is part of OMAP PM (not the generic PM)  ?

    Thanks for clarifications,

    Ran