linux-kernel - [PATCH review for 3.18 06/30] clk: wm831x: fix usleep

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Message-ID: <20170920044542.7571-6-alexander.levin@verizon.com>
Date:   Wed, 20 Sep 2017 04:45:51 +0000
From:   "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Nicholas Mc Guire <hofrat@...dl.org>,
        Stephen Boyd <sboyd@...eaurora.org>,
        "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
Subject: [PATCH review for 3.18 06/30] clk: wm831x: fix usleep_range with bad
 range

From: Nicholas Mc Guire <hofrat@...dl.org>

[ Upstream commit ed784c532a3d0959db488f40a96c5127f63d42dc ]

The delay here is not in atomic context and does not seem critical with
respect to precision, but usleep_range(min,max) with min==max results in
giving the timer subsystem no room to optimize uncritical delays. Fix
this by setting the range to 2000,3000 us.

Fixes: commit f05259a6ffa4 ("clk: wm831x: Add initial WM831x clock driver")
Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
Acked-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 drivers/clk/clk-wm831x.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk-wm831x.c b/drivers/clk/clk-wm831x.c
index ef67719f4e52..b9a0eddf44de 100644
--- a/drivers/clk/clk-wm831x.c
+++ b/drivers/clk/clk-wm831x.c
@@ -102,7 +102,8 @@ static int wm831x_fll_prepare(struct clk_hw *hw)
 	if (ret != 0)
 		dev_crit(wm831x->dev, "Failed to enable FLL: %d\n", ret);
 
-	usleep_range(2000, 2000);
+	/* wait 2-3 ms for new frequency taking effect */
+	usleep_range(2000, 3000);
 
 	return ret;
 }
-- 
2.11.0