linux-kernel - [PATCH v3 5/6] iio: pressure: hsc030pa add mandatory delay

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Message-ID: <20240211075645.28777-6-petre.rodan@subdimension.ro>
Date: Sun, 11 Feb 2024 09:56:36 +0200
From: Petre Rodan <petre.rodan@...dimension.ro>
To: linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Petre Rodan <petre.rodan@...dimension.ro>,
	Jonathan Cameron <jic23@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>
Subject: [PATCH v3 5/6] 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: Petre Rodan <petre.rodan@...dimension.ro>
---
v1 -> v3 no changes
 drivers/iio/pressure/hsc030pa.h     | 1 +
 drivers/iio/pressure/hsc030pa_i2c.c | 3 +++
 drivers/iio/pressure/hsc030pa_spi.c | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/drivers/iio/pressure/hsc030pa.h b/drivers/iio/pressure/hsc030pa.h
index f1079a70799f..56dc8e88194b 100644
--- a/drivers/iio/pressure/hsc030pa.h
+++ b/drivers/iio/pressure/hsc030pa.h
@@ -13,6 +13,7 @@
 #include <linux/iio/iio.h>
 
 #define HSC_REG_MEASUREMENT_RD_SIZE 4
+#define HSC_RESP_TIME_MS            2
 
 struct device;
 
diff --git a/drivers/iio/pressure/hsc030pa_i2c.c b/drivers/iio/pressure/hsc030pa_i2c.c
index b5810bafef40..b3fd230e71da 100644
--- a/drivers/iio/pressure/hsc030pa_i2c.c
+++ b/drivers/iio/pressure/hsc030pa_i2c.c
@@ -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;
diff --git a/drivers/iio/pressure/hsc030pa_spi.c b/drivers/iio/pressure/hsc030pa_spi.c
index 8d3441f1dcf9..818fa6303454 100644
--- a/drivers/iio/pressure/hsc030pa_spi.c
+++ b/drivers/iio/pressure/hsc030pa_spi.c
@@ -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);
 }
 
-- 
2.43.0