On Mon, Oct 26, 2015 at 11:51 AM, Michael Turquette <mturquette@xxxxxxxxxxxx> wrote: > Quoting Rafael J. Wysocki (2015-10-25 06:54:39) >> On Sun, Oct 25, 2015 at 12:06 AM, Mark Brown <broonie@xxxxxxxxxx> wrote: >> > On Sat, Oct 24, 2015 at 04:17:12PM +0200, Rafael J. Wysocki wrote: >> > >> >> Well, I'm not quite sure why exactly everyone is so focused on probing here. >> > >> > Probe deferral is really noisy even if it's working fine on a given >> > system so it's constantly being highlighted to people in a way that >> > other issues aren't if you're not directly having problems. >> > >> > There's also the understanding people had that the order things get >> > bound changes the ordering for some of the other cases (perhaps it's a >> > good idea to do that, it seems likely to be sensible?). >> >> But it really doesn't do that. Also making it do so doesn't help much >> in the cases where things can happen asynchronously (system >> suspend/resume, runtime PM). >> >> If, instead, there was a way to specify a functional dependency at the >> device registration time, it might be used to change the order of >> everything relevant, including probe. That should help to reduce the >> noise you're referring to. > > Taking it a step further, if functional dependencies were understood at > link-time then we could optimize link order as well. There are probably > lots of optimizations if we only made the effort to understand these > dependencies earlier. Do you mean the kernel link time or something else? At least in some cases the dependency information won't be known at that time, so we need a way to record a dependency at the time it becomes visible to us anyway. > Constructing the device/resource dependency graph before the device ever > boots sounds interesting to me. That's only practical if you build the kernel for a specific device. If you want a generic binary that can work with multiple different devices, that graph may very well be different for each of them. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
