> -----Oorspronkelijk bericht----- > Van: Sergei Shtylyov [mailto:sshtylyov@xxxxxxxxxxxxx] > Verzonden: vrijdag 28 maart 2008 16:15 > Aan: Atsushi Nemoto > CC: ralf@xxxxxxxxxxxxxx; linux-mips@xxxxxxxxxxxxxx; Nico Coesel > Onderwerp: Re: Alchemy power managment code. > > Hello. > > Atsushi Nemoto wrote: > > >>>Correct - and cevt-r4k won't be usable either. I guess that means > >>>you leave the user the choice between either these two or > using wait. > >>>Not nice but ... > > >> The Alchemy code doesn't even try to use CP0 counter when > >>CONFIG_PM=y if you look into > arch/mips/au1000/common/time.c... or at > >>least it didn't before Atsushi removed do_fast_pm_gettimeoffset(). > > > Oh, yes. At that time I tried to implement clocksource drivers for > > non-standard timers, but it seems I had missied Alchemy PM=y case. > > > The driver would be something like this? Completely untested ;-) > > > static cycle_t au1000_hpt_read(void) > > { > > return au_readl(SYS_TOYREAD); > > } > > > struct clocksource au1000_clocksource = { > > .name = "au1000-counter", > > .rating = 200, > > Rating should be greater than that of CP0 counter... > > > .read = au1000_hpt_read, > > .mask = CLOCKSOURCE_MASK(32), > > .flags = CLOCK_SOURCE_IS_CONTINUOUS, > > }; > > > void __init au1000_clocksource_init(unsinged long cpu_speed) { > > struct clocksource *cs = &au1000_clocksource; > > > > clocksource_set_clock(cs, cpu_speed); > > Not really, it's clocked by 32768 Hz input, so probably > not very good as a clocksource. Why not? If a 32768Hz watch crystal is connected then you'll have a stable clocksource. IIRC watch crystals are more precise than the crystals used to generate the core frequency. Nico Coesel
