Stephen Boyd <sboyd@xxxxxxxxxxxxxx> writes: > On 10/09, Rob Herring wrote: >> +Stephen who has worked on this code. >> >> On Fri, Oct 9, 2015 at 11:19 AM, Måns Rullgård <mans@xxxxxxxxx> wrote: >> > Måns Rullgård <mans@xxxxxxxxx> writes: >> > >> >> Rob Herring <robherring2@xxxxxxxxx> writes: >> >> >> >>> On Wed, Oct 7, 2015 at 11:47 AM, Måns Rullgård <mans@xxxxxxxxx> wrote: >> >>>> What would be a proper way to select a sched_clock source? I realise >> >>>> it's a Linux-specific thing and DT is supposed to be generic, but the >> >>>> information must be provided somehow. >> >>> >> >>> The kernel already has some logic to do this. Most number of bits >> >>> followed by highest frequency will be the winning sched_clock. You >> >>> might also want to look at things like always on or not. >> >> >> >> The problem is that sched_clock_register() doesn't take a pointer to be >> >> passed back to the read_sched_clock callback like most interfaces of >> >> this type do. This means the callback must use global variables set up >> >> before the register call, but at that time there's no way of knowing >> >> which one will be used. If there were a way of getting a pointer to the >> >> callback, it would be a simple matter of registering all instances and >> >> letting the kernel choose which to use. >> > >> > Anyone got a comment on this? Do I have to send a patch adding this >> > before anyone will tell me why it's a bad idea? (That method almost >> > always works.) >> >> Adding a ptr to the callback seems fine to me. >> > > Does that mean a flag day? Urgh. Pain. I'm not opposed to adding > a pointer, in fact it might be better for performance so that we > don't take a cache miss in read() functions that need to load > some pointer. We were talking about that problem a few months > ago, but nothing came of it. I've sent a patch. Let the flames begin. -- Måns Rullgård mans@xxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
