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Re: [PATCH 7/9] ARC: use fixed frequencies in arc_set_early_base_baud()

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Hi Christian,

On Tue, 2016-02-02 at 14:43 +0100, christian.ruppert@alitech.com wrote:
> Alexey Brodkin <Alexey.Brodkin@synopsys.com> wrote on 02.02.2016 13:53:26:
> > 
> > Adding Christian for Abilis TB10x clocks review.
> > 
> > On Tue, 2016-02-02 at 16:28 +0530, Vineet Gupta wrote:
> > > From: Alexey Brodkin <abrodkin@synopsys.com>
> > > 
> > > UARTs usually have fixed clock so we're switching to use of
> > > constant values instead of something derived from core clock
> > > frequency.
> > > 
> > > Among other things this will allow us to get rid of
> > > arc_{get|set}_core_freq() and switch to generic clock
> > > framework later on.
> > > 
> > > Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
> > > Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
> > > ---
> > >  arch/arc/kernel/devtree.c | 6 ++----
> > >  1 file changed, 2 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
> > > index 7e844fd8213f..e155126c79b1 100644
> > > --- a/arch/arc/kernel/devtree.c
> > > +++ b/arch/arc/kernel/devtree.c
> > > @@ -28,14 +28,12 @@ unsigned int __init arc_early_base_baud(void)
> > > 
> > >  static void __init arc_set_early_base_baud(unsigned long dt_root)
> > >  {
> > > -   unsigned int core_clk = arc_get_core_freq();
> > > -
> > >     if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x"))
> > > -      arc_base_baud = core_clk/3;
> > > +      arc_base_baud = 166666667;   /* Fixed 166.7MHz clk (TB10x) */
> 
> Actually, (int)core_clk/(int)3 is 166666666 not 166666667.
> I seem to remember that this rounding detail did make a difference at some 
> point. Unluckily, the details are long forgotten in the mist of time...

Interesting :)

I did that rounding intentionally hoping for the best.
But so good we've got your valuable input before it's too late.

-Alexey

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[PATCH 0/9] ARC clockevent/clocksource modernization Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:00 +0100
  [PATCH 2/9] ARC: [dts] Introduce Timer bindings Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:00 +0100
    Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 13:50 +0100
    Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 14:20 +0100
      Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Vineet Gupta <vgupta@synopsys.com> - 2016-02-02 15:30 +0100
        Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 16:40 +0100
          Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-03 00:00 +0100
            Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-03 14:50 +0100
              Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-03 15:00 +0100
    Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Rob Herring <robh@kernel.org> - 2016-02-02 23:10 +0100
      Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-03 09:10 +0100
        Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Rob Herring <robh@kernel.org> - 2016-02-03 16:40 +0100
  [PATCH 6/9] ARC: clocksource: DT based probe Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
    Re: [PATCH 6/9] ARC: clocksource: DT based probe Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-02-08 13:20 +0100
      Re: [PATCH 6/9] ARC: clocksource: DT based probe Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-08 13:30 +0100
  [PATCH 3/9] ARC: clockevent: switch to cpu notifier for clockevent setup Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
  [PATCH 9/9] ARC: RIP arc_{get|set}_core_freq() clk API Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
  [PATCH 4/9] ARC: clockevent: Prepare for DT based probe Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
  [PATCH 7/9] ARC: use fixed frequencies in arc_set_early_base_baud() Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
    Re: [PATCH 7/9] ARC: use fixed frequencies in  arc_set_early_base_baud() Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 14:00 +0100
      Re: [PATCH 7/9] ARC: use fixed frequencies in arc_set_early_base_baud() christian.ruppert@alitech.com - 2016-02-02 15:10 +0100
        Re: [PATCH 7/9] ARC: use fixed frequencies in  arc_set_early_base_baud() Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 15:30 +0100
  [PATCH 5/9] ARC: clockevent: DT based probe Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
  [PATCH 8/9] ARC: [plat-axs] Don't use arc_{get|set}_core_freq() for manipulating core clk Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100

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