From: Chao Xie <chao.xie@marvell.com>
Date: Thu, 23 Jan 2014 02:47:41 +0000 (+0800)
Subject: clk: mmp: fix the wrong calculation formula
X-Git-Tag: firefly_0821_release~176^2~4126^2~6
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c45693a6480cee906557a9fba533a9f3c224f91e;p=firefly-linux-kernel-4.4.55.git

clk: mmp: fix the wrong calculation formula

The formula is numerator/denominator = Fin / (Fout * factor)
So
Fout = Fin * denominator / (numerator * factor).
Current clk_factor_round_rate and clk_factor_recalc_rate use
wrong formula. This patch will fix them.

Signed-off-by: Chao Xie <chao.xie@marvell.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
---

diff --git a/drivers/clk/mmp/clk-frac.c b/drivers/clk/mmp/clk-frac.c
index f6e7691c4efa..5863a37ec84d 100644
--- a/drivers/clk/mmp/clk-frac.c
+++ b/drivers/clk/mmp/clk-frac.c
@@ -40,12 +40,12 @@ static long clk_factor_round_rate(struct clk_hw *hw, unsigned long drate,
 
 	for (i = 0; i < factor->ftbl_cnt; i++) {
 		prev_rate = rate;
-		rate = (((*prate / 10000) * factor->ftbl[i].num) /
-			(factor->ftbl[i].den * factor->masks->factor)) * 10000;
+		rate = (((*prate / 10000) * factor->ftbl[i].den) /
+			(factor->ftbl[i].num * factor->masks->factor)) * 10000;
 		if (rate > drate)
 			break;
 	}
-	if (i == 0)
+	if ((i == 0) || (i == factor->ftbl_cnt))
 		return rate;
 	else
 		return prev_rate;
@@ -85,8 +85,8 @@ static int clk_factor_set_rate(struct clk_hw *hw, unsigned long drate,
 
 	for (i = 0; i < factor->ftbl_cnt; i++) {
 		prev_rate = rate;
-		rate = (((prate / 10000) * factor->ftbl[i].num) /
-			(factor->ftbl[i].den * factor->masks->factor)) * 10000;
+		rate = (((prate / 10000) * factor->ftbl[i].den) /
+			(factor->ftbl[i].num * factor->masks->factor)) * 10000;
 		if (rate > drate)
 			break;
 	}