linux-kernel - [PATCH 3.16 019/212] clk: wm831x: fix usleep

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Date:   Thu, 01 Jun 2017 16:43:15 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Charles Keepax" <ckeepax@...nsource.wolfsonmicro.com>,
        "Nicholas Mc Guire" <hofrat@...dl.org>,
        "Stephen Boyd" <sboyd@...eaurora.org>
Subject: [PATCH 3.16 019/212] clk: wm831x: fix usleep_range with bad range

3.16.44-rc1 review patch.  If anyone has any objections, please let me know.

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

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

commit ed784c532a3d0959db488f40a96c5127f63d42dc upstream.

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: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/clk/clk-wm831x.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/clk/clk-wm831x.c
+++ b/drivers/clk/clk-wm831x.c
@@ -102,7 +102,8 @@ static int wm831x_fll_prepare(struct clk
 	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;
 }