linux-kernel - [PATCH 5.4 02/62] iio: humidity: hdc100x: Add margin to the conversion time

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Message-Id: <20210816125428.285083862@linuxfoundation.org>
Date:   Mon, 16 Aug 2021 15:01:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chris Lesiak <chris.lesiak@...or.com>,
        Matt Ranostay <matt.ranostay@...sulko.com>,
        Stable@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: [PATCH 5.4 02/62] iio: humidity: hdc100x: Add margin to the conversion time

From: Chris Lesiak <chris.lesiak@...or.com>

commit 84edec86f449adea9ee0b4912a79ab8d9d65abb7 upstream.

The datasheets have the following note for the conversion time
specification: "This parameter is specified by design and/or
characterization and it is not tested in production."

Parts have been seen that require more time to do 14-bit conversions for
the relative humidity channel.  The result is ENXIO due to the address
phase of a transfer not getting an ACK.

Delay an additional 1 ms per conversion to allow for additional margin.

Fixes: 4839367d99e3 ("iio: humidity: add HDC100x support")
Signed-off-by: Chris Lesiak <chris.lesiak@...or.com>
Acked-by: Matt Ranostay <matt.ranostay@...sulko.com>
Link: https://lore.kernel.org/r/20210614141820.2034827-1-chris.lesiak@licor.com
Cc: <Stable@...r.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/iio/humidity/hdc100x.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/iio/humidity/hdc100x.c
+++ b/drivers/iio/humidity/hdc100x.c
@@ -24,6 +24,8 @@
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
 
+#include <linux/time.h>
+
 #define HDC100X_REG_TEMP			0x00
 #define HDC100X_REG_HUMIDITY			0x01
 
@@ -165,7 +167,7 @@ static int hdc100x_get_measurement(struc
 				   struct iio_chan_spec const *chan)
 {
 	struct i2c_client *client = data->client;
-	int delay = data->adc_int_us[chan->address];
+	int delay = data->adc_int_us[chan->address] + 1*USEC_PER_MSEC;
 	int ret;
 	__be16 val;
 
@@ -322,7 +324,7 @@ static irqreturn_t hdc100x_trigger_handl
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct hdc100x_data *data = iio_priv(indio_dev);
 	struct i2c_client *client = data->client;
-	int delay = data->adc_int_us[0] + data->adc_int_us[1];
+	int delay = data->adc_int_us[0] + data->adc_int_us[1] + 2*USEC_PER_MSEC;
 	int ret;
 
 	/* dual read starts at temp register */