linux-kernel - [PATCH] iio: light: as73211: Increase measurement timeout

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Date:   Wed, 9 Sep 2020 17:44:39 +0200
From:   Christian Eggers <ceggers@...i.de>
To:     Jonathan Cameron <jic23@...nel.org>
CC:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        "Peter Meerwald-Stadler" <pmeerw@...erw.net>,
        <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Christian Eggers <ceggers@...i.de>
Subject: [PATCH] iio: light: as73211: Increase measurement timeout

We found some sensors which are much slower (20% at room temperature)
than nominal. According to the data sheet, up to 27% is possible. Now I
add 33% to the nominal time out, hopefully this is enough.

Signed-off-by: Christian Eggers <ceggers@...i.de>
---
 drivers/iio/light/as73211.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/light/as73211.c b/drivers/iio/light/as73211.c
index 25e5c386d678..457bf7f4b1f4 100644
--- a/drivers/iio/light/as73211.c
+++ b/drivers/iio/light/as73211.c
@@ -259,10 +259,9 @@ static int as73211_req_data(struct as73211_data *data)
 	data->osr &= ~AS73211_OSR_SS;

 	/*
-	 * Add some extra margin for the timeout. sensor timing is not as precise
-	 * as our one ...
+	 * Add 33% extra margin for the timeout. fclk,min = fclk,typ - 27%.
 	 */
-	time_us += time_us / 8;
+	time_us += time_us / 3;
 	if (data->client->irq) {
 		ret = wait_for_completion_timeout(&data->completion, usecs_to_jiffies(time_us));
 		if (!ret) {
-- 
Christian Eggers
Embedded software developer

Arnold & Richter Cine Technik GmbH & Co. Betriebs KG
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