The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 84edec86f449adea9ee0b4912a79ab8d9d65abb7 Mon Sep 17 00:00:00 2001

From: Chris Lesiak chris.lesiak@licor.com Date: Mon, 14 Jun 2021 09:18:20 -0500 Subject: [PATCH] iio: humidity: hdc100x: Add margin to the conversion time

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@licor.com Acked-by: Matt Ranostay matt.ranostay@konsulko.com Link: https://lore.kernel.org/r/20210614141820.2034827-1-chris.lesiak@licor.com Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com

diff --git a/drivers/iio/humidity/hdc100x.c b/drivers/iio/humidity/hdc100x.c index 2a957f19048e..9e0fce917ce4 100644 --- a/drivers/iio/humidity/hdc100x.c +++ b/drivers/iio/humidity/hdc100x.c @@ -25,6 +25,8 @@ #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

@@ -166,7 +168,7 @@ static int hdc100x_get_measurement(struct hdc100x_data *data, 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;

@@ -316,7 +318,7 @@ static irqreturn_t hdc100x_trigger_handler(int irq, void *p) 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 */