• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 98 subscribers
  • Views 366 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.

Power Management - unresolved issues

ranchu
Guru 20755 points


Hello,

Is there a TI e2e forum for *linux* power management ?
This subject is very big and seems that it is not well covered, not in documents and also by forum, making the subject handling quite difficult for SW engineers. Anyway, I would like to ask some question on this subject, not yet found answer anywhere.

I am trying to configure OMAP35x , kernel linux to automatic power management, i.e. use all auto method (cpuidle, runtime PM , etc.). I have the following unresolved questions:

1. How to configure wakeup source in OMAP35x ?  for example how to configure it for gpio interrupts, timer, uart.
2. Does a wakeup source triggers only a specific device, or does it wakes up the cpu from cpuidle mode. example: if it is a gpio interrupt, what will it wake up ?
3. We use a PMIC which is responsible for lcd brightness. Does the lcd brightness will get darkened automatically ? Do I need to configure anything ? How will the lcd wakeup again ?

Thanks very much!
Ran



  • 0
    TI__Guru** 116100 points

    Hi Ran,

    Your questions are very generic to Linux and it is not device specific.

    CPUFreq (DVFS) and CPUIdle power managements are device specific. So please refer to your specific data sheet.

    Also, to know more about power management, you can refer to the device specific "power Management" chapter in TRM guide.

    http://processors.wiki.ti.com/index.php/Sitara_Linux_Training:_Power_Management

    RTC wake:

    rtcwake -d /dev/rtc0 -s 20 -m mem (20 sec)


    Linux driver code:

    if (device_may_wakeup(dev))
    ret = enable_irq_wake(info->irq);

  • 0 in reply to Titusrathinaraj Stalin
    Guru 20755 points

    Hi Titus,

    Thanks for response. 
    The TRM was not very helpful in my case, mainly because it does not describe or point to linux wiki for using the pm HW capabilities: cpufreq, cpuidle, smartreflex and runtime_pm. 

    I also do find several issues which I'm not sure if platform depended or not, for example: wakeup sources , example: echo uart0_rxd.gpio1_10=0x27,rising > standby_gpio_pad_conf, is it generic or OMAP depended ?
    I find it hard to find wiki or example, or contact support who understand PM (or just point to where I can find the answers), thus making the issue of PM support on board quite difficult.

    Thanks for your time,
    Ran