Hi Gregor!
Gregor Boirie writes:
> Adds a new per-device sysfs attribute "current_timestamp_clock" to allow
> userspace to select a particular POSIX clock for buffered samples and
> events timestamping.
> drivers/iio/humidity/dht11.c | 16 +-
The dht11 driver only uses timestamps internally. AFAICT they are not
exported to user space, so there is little point in making the clock
selectable.
What's more important: The timestamps are used to decide the validity
of cached values. I think your change introduces a bug where the driver
could report outdated (or even uninitialized) values to user space.
(Actually we switched the driver to monotonic time just recently to fix
this.)
HTH,
Harald
> diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
> index 20b500d..a9b1b87 100644
> --- a/drivers/iio/humidity/dht11.c
> +++ b/drivers/iio/humidity/dht11.c
> @@ -110,7 +110,8 @@ static unsigned char dht11_decode_byte(char *bits)
> return ret;
> }
>
> -static int dht11_decode(struct dht11 *dht11, int offset)
> +static int dht11_decode(const struct iio_dev *iio_dev, struct dht11 *dht11,
> + int offset)
> {
> int i, t;
> char bits[DHT11_BITS_PER_READ];
> @@ -133,7 +134,7 @@ static int dht11_decode(struct dht11 *dht11, int offset)
> if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum)
> return -EIO;
>
> - dht11->timestamp = ktime_get_boot_ns();
> + dht11->timestamp = iio_get_time_ns(iio_dev);
> if (hum_int < 20) { /* DHT22 */
> dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *
> ((temp_int & 0x80) ? -100 : 100);
> @@ -161,7 +162,7 @@ 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_boot_ns();
> + dht11->edges[dht11->num_edges].ts = iio_get_time_ns(iio);
> dht11->edges[dht11->num_edges++].value =
> gpio_get_value(dht11->gpio);
>
> @@ -180,8 +181,9 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
> int ret, timeres, offset;
>
> mutex_lock(&dht11->lock);
> - if (dht11->timestamp + DHT11_DATA_VALID_TIME < ktime_get_boot_ns()) {
> - timeres = ktime_get_resolution_ns();
> + if (dht11->timestamp + DHT11_DATA_VALID_TIME <
> + iio_get_time_ns(iio_dev)) {
> + timeres = iio_get_time_res(iio_dev);
> if (timeres > DHT11_MIN_TIMERES) {
> dev_err(dht11->dev, "timeresolution %dns too low\n",
> timeres);
> @@ -231,7 +233,7 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
> offset = DHT11_EDGES_PREAMBLE +
> dht11->num_edges - DHT11_EDGES_PER_READ;
> for (; offset >= 0; --offset) {
> - ret = dht11_decode(dht11, offset);
> + ret = dht11_decode(iio_dev, dht11, offset);
> if (!ret)
> break;
> }
> @@ -302,7 +304,7 @@ static int dht11_probe(struct platform_device *pdev)
> return -EINVAL;
> }
>
> - dht11->timestamp = ktime_get_boot_ns() - DHT11_DATA_VALID_TIME - 1;
> + dht11->timestamp = iio_get_time_ns(iio) - DHT11_DATA_VALID_TIME - 1;
> dht11->num_edges = -1;
--
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