On Mon, Sep 18, 2017 at 08:53:43PM +0300, Artturi Alm wrote:
> On Mon, Sep 18, 2017 at 03:41:56PM +0300, Artturi Alm wrote:
> > On Mon, Sep 18, 2017 at 11:19:09AM +0100, Stuart Henderson wrote:
> > > On 2017/09/18 04:28, Artturi Alm wrote:
> > > > Do i really need to reference datasheets, or would someone explain to me
> > > > the value of this MSB robbing?
> > >
> > > I think, if you're proposing a change, you should explain why that
> > > change should be made, rather than asking others to defend the current
> > > situation..
> > >
> >
> > guess i wasn't clear enough. of the 3 timers two are 64bit timers, of them
> > agtimer doesn't even support reading just 32bit, nor any of them do just
> > 31bits as claimed by the timercounter mask.
> > so all of them act opposite to what's written in sys/timetc.h, the last bit
> > won't be constant with these.
> >
> > amptimer's low register does have full 32bits, if it didn't, i doubt this
> > function could exist:
> > /sys/arch/arm/cortex/amptimer.c:
> > 128 uint64_t
> > 129 amptimer_readcnt64(struct amptimer_softc *sc)
> > 130 {
> > 131 uint32_t high0, high1, low;
> > 132 bus_space_tag_t iot = sc->sc_iot;
> > 133 bus_space_handle_t ioh = sc->sc_ioh;
> > 134
> > 135 do {
> > 136 high0 = bus_space_read_4(iot, ioh, GTIMER_CNT_HIGH);
> > 137 low = bus_space_read_4(iot, ioh, GTIMER_CNT_LOW);
> > 138 high1 = bus_space_read_4(iot, ioh, GTIMER_CNT_HIGH);
> > 139 } while (high0 != high1);
> > 140
> > 141 return ((((uint64_t)high1) << 32) | low);
> > 142 }
> >
> > if you google for "swpu223g" you'll find omap3430 technical reference manual
> > pdf, in it you can find the description of gptimer's TCRR register, at
> > page 2600, also it _will_ count beyond 0x7fffffff.
> >
> > you can find reference to gptimer(missed replace) from amptimer.c, i guess
> > amptimer was where agtimer got it from, so maybe just an bad copy-paste.
> >
>
> i meant to write "(missed replace?)" above, as i'm not sure,
> but now i think i know who i should have cc'ed initially.
> i'm guessing the chain has gone something like this:
> macppc||socppc->beagle's gptimer->panda's amptimer->agtimer->arm64 agtimer
>
> drahn@, would you help me out a bit here? do you know/remember about
> these enough, to ok what i've suggested(+same for arm64 agtimer) to anyone
> who could pick this up?
>
> -Artturi
>
ping? would you, just for a bit?
-Artturi
