linux-kernel - [PATCH 4.18 061/158] clk: scmi: Fix the rounding of clock rate

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Message-Id: <20180917211714.059887195@linuxfoundation.org>
Date:   Tue, 18 Sep 2018 00:41:31 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sudeep Holla <sudeep.holla@....com>,
        Amit Daniel Kachhap <amit.kachhap@....com>,
        Stephen Boyd <sboyd@...nel.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.18 061/158] clk: scmi: Fix the rounding of clock rate

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Amit Daniel Kachhap <amit.kachhap@....com>

[ Upstream commit 7a8655e19bdb3be43f6a3b4768c9b0928a2585fc ]

This fix rounds the clock rate properly by using quotient and not
remainder in the calculation. This issue was found while testing HDMI
in the Juno platform.

Fixes: 6d6a1d82eaef7 ("clk: add support for clocks provided by SCMI")
Acked-by: Sudeep Holla <sudeep.holla@....com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@....com>
Signed-off-by: Stephen Boyd <sboyd@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/clk/clk-scmi.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/drivers/clk/clk-scmi.c
+++ b/drivers/clk/clk-scmi.c
@@ -38,7 +38,6 @@ static unsigned long scmi_clk_recalc_rat
 static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
 				unsigned long *parent_rate)
 {
-	int step;
 	u64 fmin, fmax, ftmp;
 	struct scmi_clk *clk = to_scmi_clk(hw);
 
@@ -60,9 +59,9 @@ static long scmi_clk_round_rate(struct c
 
 	ftmp = rate - fmin;
 	ftmp += clk->info->range.step_size - 1; /* to round up */
-	step = do_div(ftmp, clk->info->range.step_size);
+	do_div(ftmp, clk->info->range.step_size);
 
-	return step * clk->info->range.step_size + fmin;
+	return ftmp * clk->info->range.step_size + fmin;
 }
 
 static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,