> Kevin Hilman wrote:
> >Saravana Kannan <skannan@codeaurora.org> writes:
> >
> >>Some drivers/devices might need some minimum system bus performance to
> >>provide acceptable service. Provide a PM QoS parameter to send these requests
> >>to.
> >>
> >>The new parameter is named "system bus performance" since it is generic enough
> >>for the unit of the request to be frequency, bandwidth or something else that
> >>might be appropriate. It's up to each implementation of the QoS provider to
> >>define what the unit of the request would be.
> >>
> >>Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
> >
> >With this current design, only one system-wide bus would be managed.
> >What if a platform has more than one independently scalable bus?
> >
> >I think the only scalable way to handle this kind of thing is to have
> >per-device QoS constraints that can then be combined/aggregated by parent
> >devices/busses.
> >
> >At LPC this year, I've proposed per-device QoS constraints[1] as a topic
> >for the PM mini-conf. I hope some folks from the MSM camp can be there
> >for these discussions.
> >
> >Kevin
> >
> >[1]
http://www.linuxplumbersconf.org/2010/ocw/proposals/819
>
> Yeah, I'm planning on rounding up some MSM folks for LPC this year.
> Power is a big concern for us so it would be good to join the
> discussion. Initially, I was very keen on the per-device QoS
> contraints but I've since cooled on it. For our HW, there's not a
> generic unit that can convey enough data for us to act on. At least
> not w/o lookup tables, etc., at which point the unit loses it's
> value and becomes a generic handle. I'm looking forward to a good
> group discussion on this topic. Thanks.
>
>
