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. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project -- 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
