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OMAP2/3: clock: fix fint calculation for DPLL_FREQSEL 

In OMAP35X TRM Rev 2010-05 Figure 7-18 "DPLL With EMI Reduction
Feature", it is shown that the internal frequency is calculated by
CLK_IN/(N+1). However, the value passed to _dpll_test_fint() is
already "N+1" since Linux is using the values to divide by. In the
technical reference manual, "N" is referring to the divider's register
value (0-127).

During power management testing, it was observed that programming the
wrong jitter correction value can cause the system to become unstable
and eventually crash.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
[paul@pwsan.com: added second paragraph to commit message]
Signed-off-by: Paul Walmsley <paul@pwsan.com>
This commit is contained in:
John Ogness 2011-02-22 20:00:47 -07:00 committed by Paul Walmsley
parent f5412be599
commit ea68c00e26
1 changed files with 1 additions and 1 deletions
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2
arch/arm/mach-omap2/clkt_dpll.c
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@ -77,7 +77,7 @@ static int _dpll_test_fint(struct clk *clk, u8 n)
dd = clk->dpll_data;
/* DPLL divider must result in a valid jitter correction val */
fint = clk->parent->rate / (n + 1);
fint = clk->parent->rate / n;
if (fint < DPLL_FINT_BAND1_MIN) {
pr_debug("rejecting n=%d due to Fint failure, "