Re: Montreal Linux Power Management Mini-Summit, July 13, 2009 - Meeting Notes

[Francesco VIRLINZI <francesco.virlinzi@st.com>]

Hi Linus
FYI:
I'm going to present a generic linux clock framework during the CELF-Europe
  @
http://www.embeddedlinuxconference.com/elc_europe09/sessions.html#Virlinzi

It's integrated in the LDM via platform_driver and platform_device.

It would be a proposal but it doesn't use the CPUFreq.

It uses struct clk to identify each phisical the clock in the system
  and it adds clock information to the platform_device to link each
  device to the clock it uses.

Regards
  Francesco

On 09/02/2009 12:22 AM, Linus Walleij wrote:
> 2009/7/31 Len Brown<lenb@kernel.org>:
>
>    
>> A Linux Power Management "mini-summit" was held on July 13th, 2009 -
>> on the first day of the Montreal Linux Symposium.
>> (...)
>>      
>    
>> SH running cpufreq on top of clock framework
>>         cpufreq has notifiers, clock framework does not
>>      
> Hm! Paul can you elaborate on what that was about.
>
> I've felt a need for clock notifiers and we've cheated by using
> CPUfreq because it so happens that the clocking in system-wide
> and whenever the CPU freq change so may the other clocks.
>
> But if I put code into a PrimeCell MMC/SPI/I2C driver or whatever and
> use CPUfreq that's very unelegant, and for other platforms where
> the CPU freq don't change when this particular device clk freq
> change plain misleading.
>
> A clk pre/postchange notifier pair would really help and would
> make for elegant drivers that can handle clock freq transitions.
>
> Has anyone poked at this?
>
> Linus Walleij
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