linux-kernel - [PATCH] thermal: rockchip: use the usleep

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Message-Id: <1462242230-20873-1-git-send-email-wxt@rock-chips.com>
Date:	Tue,  3 May 2016 10:23:50 +0800
From:	Caesar Wang <wxt@...k-chips.com>
To:	edubezval@...il.com
Cc:	rui.zhang@...el.com, heiko@...ech.de,
	linux-rockchip@...ts.infradead.org, huangtao@...k-chips.com,
	Caesar Wang <wxt@...k-chips.com>, linux-pm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] thermal: rockchip: use the usleep_range instead of udelay

Documentation/timers/timers-howto.txt recommends to use
usleep_range on delays > 10usec.
The usleep_range indeed reduces CPU load, since the udelay will busy wait
for enough loop cycles to achieve the desired delay.

Fixes commit b06c52db39fd ("thermal: rockchip:
handle the power sequence for tsadc controller").

Cc: Zhang Rui <rui.zhang@...el.com>
Cc: Eduardo Valentin <edubezval@...il.com>
Cc: Heiko Stuebner <heiko@...ech.de>
Suggested-by: Eduardo Valentin <edubezval@...il.com>
Signed-off-by: Caesar Wang <wxt@...k-chips.com>

---

 drivers/thermal/rockchip_thermal.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/rockchip_thermal.c b/drivers/thermal/rockchip_thermal.c
index 86a1ab0..5d491f1 100644
--- a/drivers/thermal/rockchip_thermal.c
+++ b/drivers/thermal/rockchip_thermal.c
@@ -547,10 +547,10 @@ static void rk_tsadcv3_initialize(struct regmap *grf, void __iomem *regs,
 		regmap_write(grf, GRF_TSADC_TESTBIT_L, GRF_TSADC_TSEN_PD_ON);
 		mdelay(10);
 		regmap_write(grf, GRF_TSADC_TESTBIT_L, GRF_TSADC_TSEN_PD_OFF);
-		udelay(100); /* The spec note says at least 15 us */
+		usleep_range(15, 100); /* The spec note says at least 15 us */
 		regmap_write(grf, GRF_SARADC_TESTBIT, GRF_SARADC_TESTBIT_ON);
 		regmap_write(grf, GRF_TSADC_TESTBIT_H, GRF_TSADC_TESTBIT_H_ON);
-		udelay(200); /* The spec note says at least 90 us */
+		usleep_range(90, 200); /* The spec note says at least 90 us */
 	}
 
 	if (tshut_polarity == TSHUT_HIGH_ACTIVE)
-- 
1.9.1