Re: [PATCH 0/3] MMC / PM: Make it possible to use PM QoS latency constraints

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Tuesday, March 06, 2012, Guennadi Liakhovetski wrote:
> On Tue, 6 Mar 2012, Adrian Hunter wrote:
> 
> > On 04/03/12 02:01, Rafael J. Wysocki wrote:
> > > Hi all,
> > > 
> > > The goal of this patchset is to allow user space to control the
> > > responsiveness of the MMC stack related to runtime power management.
> > 
> > I wonder why this is build into mmc and not just a generic runtime pm
> > facility. e.g.

Because of the user space interface (it doesn't necessarily make sense
for all devices) and to allow drivers to opt-in (if they don't, the interface
won't be created), which is not possible at the core level (we don't know in
advance what drivers will handle the given devices and if they will support
PM QoS).

> > 	/* Set maximum resume latency target to 100ms */
> > 	pm_runtime_set_max_latency(dev, 100);
> > 
> > And then runtime pm will create sysfs attributes etc
> 
> +1. Having to do essentially exactly the same for each driver subsystem 
> seems counterproductive.

Other subsystems need not do that in the same way.

Thanks,
Rafael