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Commit 17a2f46c authored by Abhilash Jindal's avatar Abhilash Jindal Committed by Jonathan Cameron
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iio: dht11: Use boottime 



Wall time obtained from ktime_get_real_ns is susceptible to sudden jumps due to
user setting the time or due to NTP.  Boot time is constantly increasing time
better suited for comparing two timestamps.

Signed-off-by: default avatarAbhilash Jindal <klock.android@gmail.com>
Reviewed-by: default avatarHarald Geyer <harald@ccbib.org>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent ddeb35cb

drivers/iio/humidity/dht11.c

+4 −4
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ static int dht11_decode(struct dht11 *dht11, int offset, int timeres) 
	if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum)

		return -EIO;



	dht11->timestamp = ktime_get_real_ns();

	dht11->timestamp = ktime_get_boot_ns();

	if (hum_int < 20) {  /* DHT22 */

		dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *

					((temp_int & 0x80) ? -100 : 100);
@@ -145,7 +145,7 @@ static irqreturn_t dht11_handle_irq(int irq, void *data) 


	/* TODO: Consider making the handler safe for IRQ sharing */

	if (dht11->num_edges < DHT11_EDGES_PER_READ && dht11->num_edges >= 0) {

		dht11->edges[dht11->num_edges].ts = ktime_get_real_ns();

		dht11->edges[dht11->num_edges].ts = ktime_get_boot_ns();

		dht11->edges[dht11->num_edges++].value =

						gpio_get_value(dht11->gpio);
@@ -164,7 +164,7 @@ static int dht11_read_raw(struct iio_dev *iio_dev, 
	int ret, timeres;



	mutex_lock(&dht11->lock);

	if (dht11->timestamp + DHT11_DATA_VALID_TIME < ktime_get_real_ns()) {

	if (dht11->timestamp + DHT11_DATA_VALID_TIME < ktime_get_boot_ns()) {

		timeres = ktime_get_resolution_ns();

		if (DHT11_DATA_BIT_HIGH < 2 * timeres) {

			dev_err(dht11->dev, "timeresolution %dns too low\n",
@@ -279,7 +279,7 @@ static int dht11_probe(struct platform_device *pdev) 
		return -EINVAL;

	}



	dht11->timestamp = ktime_get_real_ns() - DHT11_DATA_VALID_TIME - 1;

	dht11->timestamp = ktime_get_boot_ns() - DHT11_DATA_VALID_TIME - 1;

	dht11->num_edges = -1;



	platform_set_drvdata(pdev, iio);