Merge tag 'staging-5.4-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging

Pull IIO fixes and staging driver from Greg KH:
 "Here is a mix of a number of IIO driver fixes for 5.4-rc7, and a whole
  new staging driver.

  The IIO fixes resolve some reported issues, all are tiny.

  The staging driver addition is the vboxsf filesystem, which is the
  VirtualBox guest shared folder code. Hans has been trying to get
  filesystem reviewers to review the code for many months now, and
  Christoph finally said to just merge it in staging now as it is
  stand-alone and the filesystem people can review it easier over time
  that way.

  I know it's late for this big of an addition, but it is stand-alone.

  The code has been in linux-next for a while, long enough to pick up a
  few tiny fixes for it already so people are looking at it.

  All of these have been in linux-next with no reported issues"

* tag 'staging-5.4-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: Fix error return code in vboxsf_fill_super()
  staging: vboxsf: fix dereference of pointer dentry before it is null checked
  staging: vboxsf: Remove unused including <linux/version.h>
  staging: Add VirtualBox guest shared folder (vboxsf) support
  iio: adc: stm32-adc: fix stopping dma
  iio: imu: inv_mpu6050: fix no data on MPU6050
  iio: srf04: fix wrong limitation in distance measuring
  iio: imu: adis16480: make sure provided frequency is positive

1 files changed, 15 insertions, 14 deletions

diff --git a/drivers/iio/proximity/srf04.c b/drivers/iio/proximity/srf04.c
index 8b50d56b0a03..01eb8cc63076 100644
--- a/drivers/iio/proximity/srf04.c
+++ b/drivers/iio/proximity/srf04.c
@@ -110,7 +110,7 @@ static int srf04_read(struct srf04_data *data)
 	udelay(data->cfg->trigger_pulse_us);
 	gpiod_set_value(data->gpiod_trig, 0);
 
-	/* it cannot take more than 20 ms */
+	/* it should not take more than 20 ms until echo is rising */
 	ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
 	if (ret < 0) {
 		mutex_unlock(&data->lock);
@@ -120,7 +120,8 @@ static int srf04_read(struct srf04_data *data)
 		return -ETIMEDOUT;
 	}
 
-	ret = wait_for_completion_killable_timeout(&data->falling, HZ/50);
+	/* it cannot take more than 50 ms until echo is falling */
+	ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
 	if (ret < 0) {
 		mutex_unlock(&data->lock);
 		return ret;
@@ -135,19 +136,19 @@ static int srf04_read(struct srf04_data *data)
 
 	dt_ns = ktime_to_ns(ktime_dt);
 	/*
-	 * measuring more than 3 meters is beyond the capabilities of
-	 * the sensor
+	 * measuring more than 6,45 meters is beyond the capabilities of
+	 * the supported sensors
 	 * ==> filter out invalid results for not measuring echos of
 	 *     another us sensor
 	 *
 	 * formula:
-	 *         distance       3 m
-	 * time = ---------- = --------- = 9404389 ns
-	 *          speed       319 m/s
+	 *         distance     6,45 * 2 m
+	 * time = ---------- = ------------ = 40438871 ns
+	 *          speed         319 m/s
 	 *
 	 * using a minimum speed at -20 °C of 319 m/s
 	 */
-	if (dt_ns > 9404389)
+	if (dt_ns > 40438871)
 		return -EIO;
 
 	time_ns = dt_ns;
@@ -159,20 +160,20 @@ static int srf04_read(struct srf04_data *data)
 	 *   with Temp in °C
 	 *   and speed in m/s
 	 *
-	 * use 343 m/s as ultrasonic speed at 20 °C here in absence of the
+	 * use 343,5 m/s as ultrasonic speed at 20 °C here in absence of the
 	 * temperature
 	 *
 	 * therefore:
-	 *             time     343
-	 * distance = ------ * -----
-	 *             10^6       2
+	 *             time     343,5     time * 106
+	 * distance = ------ * ------- = ------------
+	 *             10^6         2         617176
 	 *   with time in ns
 	 *   and distance in mm (one way)
 	 *
-	 * because we limit to 3 meters the multiplication with 343 just
+	 * because we limit to 6,45 meters the multiplication with 106 just
 	 * fits into 32 bit
 	 */
-	distance_mm = time_ns * 343 / 2000000;
+	distance_mm = time_ns * 106 / 617176;
 
 	return distance_mm;
 }