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epit timer: raise precision

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Previously we used a pretty slow external clock source for the timer. This
resulted in such a low TICS_PER_MS value that the granularity wasn't
sufficient to find a setup with a precision better than 1 second error per
minute. Now we use the so-called High Frequency Reference Clock as input
with TICS_PER_MS=33333 and the timer precision is significantly < 1 second per
minute.

Fixes #1805
This commit is contained in:
Martin Stein 2015-12-02 15:34:00 +01:00 committed by Christian Helmuth
parent 01643ccd94
commit 492bd39619
1 changed files with 3 additions and 3 deletions
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6
repos/base/include/spec/epit/drivers/timer_base.h
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@ -29,7 +29,7 @@ class Genode::Epit_base : public Mmio
{
protected:
enum { TICS_PER_MS = 32 };
enum { TICS_PER_MS = 33333 };
/**
* Control register
@ -69,7 +69,7 @@ class Genode::Epit_base : public Mmio
struct Clk_src : Bitfield<24, 2> /* select clock input */
{
enum { IPG_CLK_32K = 3 };
enum { HIGH_FREQ_REF_CLK = 2 };
};
/**
@ -89,7 +89,7 @@ class Genode::Epit_base : public Mmio
Doz_en::bits(0) |
Stop_en::bits(0) |
Om::bits(Om::DISCONNECTED) |
Clk_src::bits(Clk_src::IPG_CLK_32K);
Clk_src::bits(Clk_src::HIGH_FREQ_REF_CLK);
}
};