linux-kernel - [PATCH v3] OMAP2/3: clock: fix fint calculation for DPLL

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Date:	Fri, 21 Jan 2011 09:33:33 +0100
From:	John Ogness <john.ogness@...utronix.de>
To:	Tony Lindgren <tony@...mide.com>
Cc:	balbi@...com
Subject: [PATCH v3] OMAP2/3: clock: fix fint calculation for DPLL_FREQSEL

From: John Ogness <john.ogness@...utronix.de>

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).

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
patch v3:
Patch against linux-next-20110121.
I have improved the commit message so that it is acceptable for the
git commit log.

 arch/arm/mach-omap2/clkt_dpll.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mach-omap2/clkt_dpll.c b/arch/arm/mach-omap2/clkt_dpll.c
index 337392c..acb7ae5 100644
--- a/arch/arm/mach-omap2/clkt_dpll.c
+++ b/arch/arm/mach-omap2/clkt_dpll.c
@@ -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, "
-- 
1.5.6.5
--
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