linux-kernel - [PATCH RFC] ASoC: rt5663: use msleep() for long delay loop

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Date:   Wed, 11 Jan 2017 16:03:13 +0100
From:   Nicholas Mc Guire <hofrat@...dl.org>
To:     Bard Liao <bardliao@...ltek.com>
Cc:     Oder Chiou <oder_chiou@...ltek.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org, Nicholas Mc Guire <hofrat@...dl.org>
Subject: [PATCH RFC] ASoC: rt5663: use msleep() for long delay loop

As the overall delay is in range of seconds and the wait granularity
is 10ms msleep() seems more reasonable than to put load on the highres
timer subsystem.

Fixes: commit df7c52168ee1 ("ASoC: add rt5663 codec driver")
Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
---
Problem was found by cocinelle script.

This does throw a checkpatch warning with:
WARNING: msleep < 20ms can sleep for up to 20ms;"
but since this is in a loop and the intended granularity is
10ms with up to 2 seconds total delay this seems ok.

Patch was compile tested with: x86_64_defconfig + CONFIG_COMPILE_TEST=y
SND_SOC=m + SND_SOC_ALL_CODECS=m (implies SND_SOC_RT5663=m)

Patch is aginast 4.10-rc3 (localversion-next is next-20170111)

 sound/soc/codecs/rt5663.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/sound/soc/codecs/rt5663.c b/sound/soc/codecs/rt5663.c
index a32508d..3bdb62b 100644
--- a/sound/soc/codecs/rt5663.c
+++ b/sound/soc/codecs/rt5663.c
@@ -2982,7 +2982,8 @@ static void rt5663_v2_calibrate(struct rt5663_priv *rt5663)
 
 static void rt5663_calibrate(struct rt5663_priv *rt5663)
 {
-	int value, count;
+	int value;
+	unsigned long timeout;
 
 	regmap_write(rt5663->regmap, RT5663_RC_CLK, 0x0280);
 	regmap_write(rt5663->regmap, RT5663_GLB_CLK, 0x8000);
@@ -3025,17 +3026,15 @@ static void rt5663_calibrate(struct rt5663_priv *rt5663)
 	regmap_write(rt5663->regmap, RT5663_HP_CALIB_3, 0x06c2);
 	regmap_write(rt5663->regmap, RT5663_HP_CALIB_1_1, 0x7b00);
 	regmap_write(rt5663->regmap, RT5663_HP_CALIB_1_1, 0xfb00);
-	count = 0;
-	while (true) {
+
+	/* allow the write completion to take up to 2s */
+	timeout = jiffies + msecs_to_jiffies(2000);
+	while (time_is_after_jiffies(timeout)) {
 		regmap_read(rt5663->regmap, RT5663_HP_CALIB_1_1, &value);
 		if (value & 0x8000)
-			usleep_range(10000, 10005);
+			msleep(10);
 		else
 			break;
-
-		if (count > 200)
-			return;
-		count++;
 	}
 }
 
-- 
2.1.4