AM335x Force OPP100 during boot

Avinash Kumar33

Other Parts Discussed in Thread: AM3351

Hi All,

I am working on power management of an AM3351 based battery power board. We are thinking of running applications all the time on "conservative" governor or forced OPP50. However, we also want a boot as soon as possible and hence, want to explore the possibility of booting in OPP100 to see if it decreases boot-time.

1. Currently, the board boots by default in "ondemand" governor and the board is running at OPP50 after boot. If we change this to OPP100 (static/forced), will it help in decreasing boot-time?

2. In any case, could you please provide help/resources to force the board to boot in OPP100? I have tried applying the patch on this link: but I think this is meant for an older version of U-Boot. The patch is failing to apply automatically and I am not able to apply it manually as the code is quite different.

Thanks and Regards,

Avinash

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi,

The wiki for the latest kernels is this: processors.wiki.ti.com/.../Linux_Core_Power_Management_User's_Guide_(v4.1) I will ask the software team to comment on this too.

0 Yordan Kovachev over 10 years ago

TI__Guru**** 161600 points

Hi,

Avinash Kumar33 said:
1. Currently, the board boots by default in "ondemand" governor and the board is running at OPP50 after boot. If we change this to OPP100 (static/forced), will it help in decreasing boot-time?

Forcing the device to OPP100 will not help you in decreasing the boot time. Boot time optimization consists mainly of removing unnecessary functionality from bootloader, kernel & filesystem and optimizing the remaining functionalities.

You could also implement falcon mode in your u-boot, so that you will skip the u-boot stage, saving about 4-5 seconds. Your boot procedure will be ROM Code -> MLO -> Kernel, instead of ROM Code -> MLO -> U-Boot -> Kernel.

For further tips youc an check the following TI Wikis:
http://processors.wiki.ti.com/index.php/Boot_Time_Optimization

http://processors.wiki.ti.com/index.php/Optimize_Linux_Boot_Time

Or any other linux tutorial, i.e.:
http://elinux.org/Boot_Time

http://free-electrons.com/doc/training/boot-time/boot-time-slides.pdf

Hope this helps.

Best Regards,
Yordan

0 Avinash Kumar33 over 10 years ago in reply to Yordan Kovachev

Prodigy 160 points

Thank you for the information. I had tried reducing Kernel inbuilt modules and reduced "rcS" and "rc5" levels to whatever was absolutely needed. Falcon Mode was new for me and I will definitely try it out.

Apart from that, I checked booting with OPP100 and you are right - it makes no difference to the boot time.

Regards,
Avinash

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AM335x Force OPP100 during boot