Port-arm archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: beaglebone: changing cpu frequency

On 1 Aug 2013, at 3:03 AM, Matt Thomas <matt%3am-software.com@localhost> wrote:

> I still need a good method to get the powersource from the tps65217pmic so
> I can limit the frequencies when power is limited.

The power source is checked in the driver, but it's only used to print the 
current source during attachment. The value of this register is never checked 
again later.

I think we have at least two ways to do it:

- Make TPS65217 generate an interrupt upon power source change. The interrupt 
line from TPS is connected to NNMI input on Sitara. I'm not really sure if it's 
a good idea to generate interrupt on a line that is labeled "NNMI", sounds 
dangerous (but it's not like I've actually checked what happens if you trigger 

- Just make an additional sysmon indicator and poll the value of TPS register 
as a part of sysmon refresh in tps65217pmic driver. Then send an event to 
powerd(8) upon change of the power source. Possibly additional 
sensor_powersource should be defined to make this an elegant solution. The 
powerd(8) could react and change CPU speed via script that writes to sysctl.

Best regards,
Radoslaw Kujawa

Attachment: signature.asc
Description: Message signed with OpenPGP using GPGMail

Home | Main Index | Thread Index | Old Index