On Sat, 2013-06-08 at 03:52 +0200, Rafael J. Wysocki wrote: > On Saturday, June 08, 2013 09:36:03 AM Yanmin Zhang wrote: > > On Sat, 2013-06-08 at 03:30 +0200, Rafael J. Wysocki wrote: > > > On Friday, June 07, 2013 06:16:25 PM Greg KH wrote: > > > > On Sat, Jun 08, 2013 at 08:42:12AM +0800, Yanmin Zhang wrote: > > > > > On Fri, 2013-06-07 at 12:36 +0200, Rafael J. Wysocki wrote: > > > > > > On Friday, June 07, 2013 04:20:30 PM [email protected] wrote: > > > > > > > dpm_run_callback is used in other stages of power states changing. > > > > > > > It provides debug info message and time measurement when call > > > > > > > these > > > > > > > callback. We also want to benefit ->prepare and ->complete. > > > > > > > > > > > > > > [PATCH 1/2] PM: use dpm_run_callback in device_prepare > > > > > > > [PATCH 2/2] PM: add dpm_run_callback_void and use it in > > > > > > > device_complete > > > > > > > > > > > > Is this an "Oh, why don't we do that?" series, or is it useful for > > > > > > anything > > > > > > in practice? I'm asking, because we haven't added that stuff to > > > > > > start with > > > > > > since we didn't see why it would be useful to anyone. > > > > > > > > > > > > And while patch [1/2] reduces the code size (by 1 line), so I can > > > > > > see some > > > > > > (tiny) benefit from applying it, patch [2/2] adds more code and is > > > > > > there any > > > > > > paractical reason? > > > > > Sometimes, suspend-to-ram path spends too much time (either suspend > > > > > slowly > > > > > or wakeup slowly) and we need optimize it. > > > > > With the 2 patches, we could collect initcall_debug printk info and > > > > > manually > > > > > check what prepare/complete callbacks consume too much time. > > > > > > > > But initcall information is for initialization stuff, not suspend/resume > > > > things, right? Doesn't the existing tools for parsing this choke if it > > > > sees the information at suspend/resume time? > > > > > > We've been using that for suspend/resume for quite some time too, but not > > > for the prepare/complete phases (because we still believe that's not > > > really > > > useful for them). > > > > > > Well, I'll be handling patches changing code under drivers/base/power, > > > I promise. :-) > > > > > > I've been doing that for quite a few years now ... > > Yes, indeed. Power is one of the most important features on embedded > > devices. > > Lots of smart phones don't really go through the full cycles of > > suspend-to-ram. > > We are following the full steps of the suspend. > > But if you go through the code, you'll see that alomost no drivers actually > implemet .prepare() and .complete(). Some subsystems do, but they really > don't > take too much time to execute. Which means that your patches with > initcall_debug will add quite a pile of useless garbage to the kernel log Does that mean we need add more log levels around such info instead of just having or not having?
Yanmin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
