Re: driver model, duplicate names question

From: Greg KH
Date: Tue Jul 16 2013 - 15:37:37 EST


On Tue, Jul 16, 2013 at 12:33:03PM -0700, Srinivas Pandruvada wrote:
> >> +Example Sys-FS Interface
> >> +
> >> +/sys/class/power_cap/intel-rapl
> >> +âââ package-0
> >> +â âââ constraint-0
> >> +â â âââ name
> >> +â â âââ power_limit_uw
> >> +â â âââ time_window_us
> >> +â âââ constraint-1
> >> +â â âââ name
> >> +â â âââ power_limit_uw
> >> +â â âââ time_window_us
> >> +â âââ core
> >> +â â âââ constraint-0
> >> +â â â âââ name
> >> +â â â âââ power_limit_uw
> >> +â â â âââ time_window_us
> >> +â â âââ energy_uj
> >> +â â âââ max_energy_range_uj
> >> +â âââ dram
> >> +â â âââ constraint-0
> >> +â â â âââ name
> >> +â â â âââ power_limit_uw
> >> +â â â âââ time_window_us
> >> +â â âââ energy_uj
> >> +â â âââ max_energy_range_uj
> >> +â âââ energy_uj
> >> +â âââ max_energy_range_uj
> >> +â âââ max_power_range_uw
> >> +âââ package-1
> >> +â âââ constraint-0
> >> +â â âââ name
> >> +â â âââ power_limit_uw
> >> +â â âââ time_window_us
> >> +â âââ constraint-1
> >> +â â âââ name
> >> +â â âââ power_limit_uw
> >> +â â âââ time_window_us
> >> +â âââ core
> >> +â â âââ constraint-0
> >> +â â â âââ name
> >> +â â â âââ power_limit_uw
> >> +â â â âââ time_window_us
> >> +â â âââ energy_uj
> >> +â â âââ max_energy_range_uj
> >> +â âââ dram
> >> +â â âââ constraint-0
> >> +â â â âââ name
> >> +â â â âââ power_limit_uw
> >> +â â â âââ time_window_us
> >> +â â âââ energy_uj
> >> +â â âââ max_energy_range_uj
> >> +â âââ energy_uj
> >> +â âââ max_energy_range_uj
> >> +â âââ max_power_range_uw
> >> +âââ power
> >> +â âââ async
> >> +â âââ autosuspend_delay_ms
> >> +â âââ control
> >> +â âââ runtime_active_kids
> >> +â âââ runtime_active_time
> >> +â âââ runtime_enabled
> >> +â âââ runtime_status
> >> +â âââ runtime_suspended_time
> >> +â âââ runtime_usage
> >> +âââ subsystem -> ../../../../class/power_cap
> >> +âââ uevent
> > Ick. Rewrite this to use a bus and you should be fine, right? Don't
> > use a class, a class is only to be used if you have a device that is a
> > specific "type of thing". Like a tty device, it is a class, as lots of
> > different "real" devices can have tty ports on them (usb, pci, pcmcia,
> > platform, etc.)
> >
> > Rethink this using a bus and see if that solves your issues. You get a
> > hierarchy with that. And you can have different "types" of devices on
> > your bus, making it easy to tell the difference between a "package" and
> > a "constraint".
> >
> > Does that help?
> I will experiment your suggestion. I see this class analogous to
> "/sys/class/thermal",
> , where the thermal class provides a set of consistent interface for all
> thermal devices.

But thermal devices are not "real" at all. There are just a number of
"cooling devices" on a virtual bus and not attached to any type of a
real device at all.

There's also no hierarchy that I can see with the thermal class, but you
want to have this, so you will have to do something different because
classes do not have hierarchies.

So try using a device and a bus and see if that helps out. If not,
please let me know.

thanks,

greg k-h
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