linux-kernel - [PATCH v2] extcon: arizona: Wait for any running HPDETs to complete on jack removal

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Date:   Wed, 25 Jan 2017 09:34:06 +0000
From:   Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
To:     <cw00.choi@...sung.com>
CC:     <myungjoo.ham@...sung.com>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.wolfsonmicro.com>
Subject: [PATCH v2] extcon: arizona: Wait for any running HPDETs to complete on jack removal

As the HPDET can't be aborted mid way through we should not allow any new
insertion to be processed until the previous HPDET has finished. It is very
unlikely but with low enough debounce settings you could start a new HPDET
before the old one has completed, which results in an erroneous reading.

Signed-off-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
---

Changes since v1:
 - Added defines for the count and delay
 - Added a comment to explain why we call arizona_hpdet_wait

Thanks,
Charles

 drivers/extcon/extcon-arizona.c | 45 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/extcon/extcon-arizona.c b/drivers/extcon/extcon-arizona.c
index ed78b7c..df98d84 100644
--- a/drivers/extcon/extcon-arizona.c
+++ b/drivers/extcon/extcon-arizona.c
@@ -1049,6 +1049,42 @@ static void arizona_hpdet_work(struct work_struct *work)
 	mutex_unlock(&info->lock);
 }
 
+#define ARIZONA_HPDET_WAIT_COUNT 15
+#define ARIZONA_HPDET_WAIT_DELAY_MS 20
+
+static int arizona_hpdet_wait(struct arizona_extcon_info *info)
+{
+	struct arizona *arizona = info->arizona;
+	unsigned int val;
+	int i, ret;
+
+	for (i = 0; i < ARIZONA_HPDET_WAIT_COUNT; i++) {
+		ret = regmap_read(arizona->regmap, ARIZONA_HEADPHONE_DETECT_2,
+				  &val);
+		if (ret) {
+			dev_err(arizona->dev,
+				"Failed to read HPDET state: %d\n", ret);
+			return ret;
+		}
+
+		switch (info->hpdet_ip_version) {
+		case 0:
+			if (val & ARIZONA_HP_DONE)
+				return 0;
+			break;
+		default:
+			if (val & ARIZONA_HP_DONE_B)
+				return 0;
+			break;
+		}
+
+		msleep(ARIZONA_HPDET_WAIT_DELAY_MS);
+	}
+
+	dev_err(arizona->dev, "HPDET did not appear to complete\n");
+	return -ETIMEDOUT;
+}
+
 static irqreturn_t arizona_jackdet(int irq, void *data)
 {
 	struct arizona_extcon_info *info = data;
@@ -1155,6 +1191,15 @@ static irqreturn_t arizona_jackdet(int irq, void *data)
 					"Removal report failed: %d\n", ret);
 		}
 
+		/*
+		 * If the jack was removed during a headphone detection we
+		 * need to wait for the headphone detection to finish, as
+		 * it can not be aborted. We don't want to be able to start
+		 * a new headphone detection from a fresh insert until this
+		 * one is finished.
+		 */
+		arizona_hpdet_wait(info);
+
 		regmap_update_bits(arizona->regmap,
 				   ARIZONA_JACK_DETECT_DEBOUNCE,
 				   ARIZONA_MICD_CLAMP_DB | ARIZONA_JD1_DB,
-- 
2.1.4