Commit df3186e8 authored by Petre Rodan's avatar Petre Rodan Committed by Jonathan Cameron
Browse files

iio: pressure: hsc030pa add mandatory delay 

Add a mandatory 2ms delay between consecutive chip reads.

A Technical Note pdf specifies that the measurement cycle in these
chips takes around 1.26ms. By adding this 2ms delay we make sure that
we never get stale measurements.

For more details, please see "Figure 1" in the pdf below:

https://prod-edam.honeywell.com/content/dam/honeywell-edam/sps/siot/en-us/products/sensors/pressure-sensors/common/documents/sps-siot-sleep-mode-technical-note-008286-1-en-ciid-155793.pdf



Signed-off-by: default avatarPetre Rodan <petre.rodan@subdimension.ro>
Link: https://lore.kernel.org/r/20240211075645.28777-6-petre.rodan@subdimension.ro


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent b0e42c9e

drivers/iio/pressure/hsc030pa.h

+1 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/iio/iio.h>



#define HSC_REG_MEASUREMENT_RD_SIZE 4

#define HSC_RESP_TIME_MS            2



struct device;

drivers/iio/pressure/hsc030pa_i2c.c

+3 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
 * Datasheet: https://prod-edam.honeywell.com/content/dam/honeywell-edam/sps/siot/en-us/products/sensors/pressure-sensors/common/documents/sps-siot-sleep-mode-technical-note-008286-1-en-ciid-155793.pdf

 */



#include <linux/delay.h>

#include <linux/device.h>

#include <linux/errno.h>

#include <linux/i2c.h>
@@ -25,6 +26,8 @@ static int hsc_i2c_recv(struct hsc_data *data) 
	struct i2c_msg msg;

	int ret;



	msleep_interruptible(HSC_RESP_TIME_MS);



	msg.addr = client->addr;

	msg.flags = client->flags | I2C_M_RD;

	msg.len = HSC_REG_MEASUREMENT_RD_SIZE;

drivers/iio/pressure/hsc030pa_spi.c

+2 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
 * Datasheet: https://prod-edam.honeywell.com/content/dam/honeywell-edam/sps/siot/en-us/products/sensors/pressure-sensors/common/documents/sps-siot-sleep-mode-technical-note-008286-1-en-ciid-155793.pdf

 */



#include <linux/delay.h>

#include <linux/device.h>

#include <linux/mod_devicetable.h>

#include <linux/module.h>
@@ -28,6 +29,7 @@ static int hsc_spi_recv(struct hsc_data *data) 
		.len = HSC_REG_MEASUREMENT_RD_SIZE,

	};



	msleep_interruptible(HSC_RESP_TIME_MS);

	return spi_sync_transfer(spi, &xfer, 1);

}