From: Abel Vesa <abel.vesa@nxp.com>
To: Stephen Boyd <sboyd@kernel.org>, Lucas Stach <l.stach@pengutronix.de>
Cc: Abel Vesa <abel.vesa@nxp.com>, Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Fabio Estevam <fabio.estevam@nxp.com>,
dl-linux-imx <linux-imx@nxp.com>,
Michael Turquette <mturquette@baylibre.com>,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>,
"open list:COMMON CLK FRAMEWORK" <linux-clk@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>
Subject: [PATCH] clk: imx: Fix fractional clock set rate computation
Date: Fri, 18 Jan 2019 12:54:13 +0000 [thread overview]
Message-ID: <1547816041-14200-1-git-send-email-abel.vesa@nxp.com> (raw)
Before multiplying by PLL_FRAC_DENOM, the temp64 needs to be
temp64 = rate * 2 - divfi * parent_rate * 8, instead of:
temp64 = (rate * 2 - divfi) * parent_rate
Fixes: 6209624b9a5c1e ("clk: imx: Add fractional PLL output clock")
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
---
drivers/clk/imx/clk-frac-pll.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/clk/imx/clk-frac-pll.c b/drivers/clk/imx/clk-frac-pll.c
index 0026c39..76b9eb1 100644
--- a/drivers/clk/imx/clk-frac-pll.c
+++ b/drivers/clk/imx/clk-frac-pll.c
@@ -155,13 +155,14 @@ static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
{
struct clk_frac_pll *pll = to_clk_frac_pll(hw);
u32 val, divfi, divff;
- u64 temp64 = parent_rate;
+ u64 temp64;
int ret;
parent_rate *= 8;
rate *= 2;
divfi = rate / parent_rate;
- temp64 *= rate - divfi;
+ temp64 = parent_rate * divfi;
+ temp64 = rate - temp64;
temp64 *= PLL_FRAC_DENOM;
do_div(temp64, parent_rate);
divff = temp64;
--
2.7.4
next reply other threads:[~2019-01-18 12:54 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-18 12:54 Abel Vesa [this message]
2019-01-24 19:17 ` Stephen Boyd
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