From: Pete Popov <ppopov@mvista.com>
To: Bob Lees <bob@diamond.demon.co.uk>
Cc: Dan Malek <dan@embeddededge.com>, linux-mips@linux-mips.org
Subject: Re: Frequency (cpu speed) control on AU1100
Date: Tue, 30 Mar 2004 14:48:34 -0800 [thread overview]
Message-ID: <4069F942.5090202@mvista.com> (raw)
In-Reply-To: <200403302338.08735.bob@diamond.demon.co.uk>
Bob Lees wrote:
>On Tuesday 30 March 2004 22:56, Dan Malek wrote:
>
>
>>Bob Lees wrote:
>> > ....I suspect I am
>>
>>
>>>missing something somewhere, but I can't find any references to cpu speed
>>>control for the MIPS processors, specically the au1x range.
>>>
>>>
>>The Au1xxx has a PLL that multiplies the incoming 12 MHz clock up to the
>>internal frequency. Just be aware there are lots of peripheral clocks
>>and bus clocks derived from this internal frequency. There is code
>>in the kernel power management to allow changing the frequency during
>>operation of Linux, but I don't know how well it works today as I have
>>not tested that for quite some time.
>>
>>Thanks.
>> -- Dan
>>
>>
>
>Thanks Dan & Pete for the prompt response.
>
>I have tried the /proc/sys/pm/freq interface and by putting a bogomips calc
>into power.c, it appears to indicate a change in core frequency. I think
>your caution may be well founded as I got input overruns on the serial
>console when I took the speed down to 84MHz, good character recognition
>though, so it was an input buffer speed issue.
>
>Also I can see an approx 40-50mA change in current from 84 to 396MHz which
>indicates something is changing. Supply is at 5 volts thru a simple switcher
>down to 3.3 volts on the Aurora board. This is with nothing else running and
>an nfs filesystem. As part of monitoring current I am seeing an anomoly:
>namely after boot is complete and system is quiesent, at apparently 396MHz,
>the current is 200mA, now after playing with the freq control the current at
>396MHz stabalises at around 250mA. Verrry strange - any thoughts??
>
>
Is the 250mA after you've done a new power cycle, which doesn't make
sense, or after you scale down to 84 and back up to 396MHz?
>On another topic, what state is the IRDA driver in?
>
It works. Check out the IrDA readme on
linux-mips.org:/pub/linux/mips/people/ppopov/2.4. I've tested two boards
back to back using the network layer at FIR speeds, and a board to palm
pilot using SIR. It's all in the readme.
>This is building from the
>patched 2.4.25 kernel on your site Dan. And a big thank you for this source
>of a patched kernel and build tools.
>
>
Pete
next prev parent reply other threads:[~2004-03-30 22:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-30 20:37 Frequency (cpu speed) control on AU1100 Bob Lees
2004-03-30 21:14 ` Pete Popov
2004-03-30 21:56 ` Dan Malek
2004-03-30 22:38 ` Bob Lees
2004-03-30 22:48 ` Pete Popov [this message]
2004-03-31 14:33 ` Bob Lees
2004-03-30 23:26 ` Dan Malek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4069F942.5090202@mvista.com \
--to=ppopov@mvista.com \
--cc=bob@diamond.demon.co.uk \
--cc=dan@embeddededge.com \
--cc=linux-mips@linux-mips.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox