<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/iio, branch v5.5</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>iio: light: vcnl4000: Fix scale for vcnl4040</title>
<updated>2020-01-13T11:08:40+00:00</updated>
<author>
<name>Guido Günther</name>
<email>agx@sigxcpu.org</email>
</author>
<published>2019-12-27T10:22:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=bc80573ea25bb033a58da81b3ce27205b97c088e'/>
<id>bc80573ea25bb033a58da81b3ce27205b97c088e</id>
<content type='text'>
According to the data sheet the ambient sensor's scale is 0.12 lux/step
(not 0.024 lux/step as used by vcnl4200) when the integration time is
80ms. The integration time is currently hardcoded in the driver to that
value.

See p. 8 in https://www.vishay.com/docs/84307/designingvcnl4040.pdf

Fixes: 5a441aade5b3 ("iio: light: vcnl4000 add support for the VCNL4040 proximity and light sensor")
Signed-off-by: Guido Günther &lt;agx@sigxcpu.org&gt;
Reviewed-by: Marco Felsch &lt;m.felsch@pengutronix.de&gt;
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
According to the data sheet the ambient sensor's scale is 0.12 lux/step
(not 0.024 lux/step as used by vcnl4200) when the integration time is
80ms. The integration time is currently hardcoded in the driver to that
value.

See p. 8 in https://www.vishay.com/docs/84307/designingvcnl4040.pdf

Fixes: 5a441aade5b3 ("iio: light: vcnl4000 add support for the VCNL4040 proximity and light sensor")
Signed-off-by: Guido Günther &lt;agx@sigxcpu.org&gt;
Reviewed-by: Marco Felsch &lt;m.felsch@pengutronix.de&gt;
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>iio: buffer: align the size of scan bytes to size of the largest element</title>
<updated>2020-01-13T11:08:37+00:00</updated>
<author>
<name>Lars Möllendorf</name>
<email>lars.moellendorf@plating.de</email>
</author>
<published>2019-12-13T13:50:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=883f616530692d81cb70f8a32d85c0d2afc05f69'/>
<id>883f616530692d81cb70f8a32d85c0d2afc05f69</id>
<content type='text'>
Previous versions of `iio_compute_scan_bytes` only aligned each element
to its own length (i.e. its own natural alignment). Because multiple
consecutive sets of scan elements are buffered this does not work in
case the computed scan bytes do not align with the natural alignment of
the first scan element in the set.

This commit fixes this by aligning the scan bytes to the natural
alignment of the largest scan element in the set.

Fixes: 959d2952d124 ("staging:iio: make iio_sw_buffer_preenable much more general.")
Signed-off-by: Lars Möllendorf &lt;lars.moellendorf@plating.de&gt;
Reviewed-by: Lars-Peter Clausen &lt;lars@metafoo.de&gt;
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Previous versions of `iio_compute_scan_bytes` only aligned each element
to its own length (i.e. its own natural alignment). Because multiple
consecutive sets of scan elements are buffered this does not work in
case the computed scan bytes do not align with the natural alignment of
the first scan element in the set.

This commit fixes this by aligning the scan bytes to the natural
alignment of the largest scan element in the set.

Fixes: 959d2952d124 ("staging:iio: make iio_sw_buffer_preenable much more general.")
Signed-off-by: Lars Möllendorf &lt;lars.moellendorf@plating.de&gt;
Reviewed-by: Lars-Peter Clausen &lt;lars@metafoo.de&gt;
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>iio: chemical: pms7003: fix unmet triggered buffer dependency</title>
<updated>2020-01-13T11:08:32+00:00</updated>
<author>
<name>Tomasz Duszynski</name>
<email>tduszyns@gmail.com</email>
</author>
<published>2019-12-13T21:38:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=217afe63ccf445fc220e5ef480683607b05c0aa5'/>
<id>217afe63ccf445fc220e5ef480683607b05c0aa5</id>
<content type='text'>
IIO triggered buffer depends on IIO buffer which is missing from Kconfig
file. This should go unnoticed most of the time because there's a
chance something else has already enabled buffers. In some rare cases
though one might experience kbuild warnings about unmet direct
dependencies and build failures due to missing symbols.

Fix this by selecting IIO_BUFFER explicitly.

Signed-off-by: Tomasz Duszynski &lt;tduszyns@gmail.com&gt;
Fixes: a1d642266c14 ("iio: chemical: add support for Plantower PMS7003 sensor")
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
IIO triggered buffer depends on IIO buffer which is missing from Kconfig
file. This should go unnoticed most of the time because there's a
chance something else has already enabled buffers. In some rare cases
though one might experience kbuild warnings about unmet direct
dependencies and build failures due to missing symbols.

Fix this by selecting IIO_BUFFER explicitly.

Signed-off-by: Tomasz Duszynski &lt;tduszyns@gmail.com&gt;
Fixes: a1d642266c14 ("iio: chemical: add support for Plantower PMS7003 sensor")
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>iio: imu: st_lsm6dsx: Fix selection of ST_LSM6DS3_ID</title>
<updated>2020-01-13T11:08:28+00:00</updated>
<author>
<name>Stephan Gerhold</name>
<email>stephan@gerhold.net</email>
</author>
<published>2019-12-16T12:41:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fb4fbc8904e786537e29329d791147389e1465a2'/>
<id>fb4fbc8904e786537e29329d791147389e1465a2</id>
<content type='text'>
At the moment, attempting to probe a device with ST_LSM6DS3_ID
(e.g. using the st,lsm6ds3 compatible) fails with:

    st_lsm6dsx_i2c 1-006b: unsupported whoami [69]

... even though 0x69 is the whoami listed for ST_LSM6DS3_ID.

This happens because st_lsm6dsx_check_whoami() also attempts
to match unspecified (zero-initialized) entries in the "id" array.
ST_LSM6DS3_ID = 0 will therefore match any entry in
st_lsm6dsx_sensor_settings (here: the first), because none of them
actually have all 12 entries listed in the "id" array.

Avoid this by additionally checking if "name" is set,
which is only set for valid entries in the "id" array.

Note: Although the problem was introduced earlier it did not surface until
commit 52f4b1f19679 ("iio: imu: st_lsm6dsx: add support for accel/gyro unit of lsm9ds1")
because ST_LSM6DS3_ID was the first entry in st_lsm6dsx_sensor_settings.

Fixes: d068e4a0f921 ("iio: imu: st_lsm6dsx: add support to multiple devices with the same settings")
Cc: &lt;stable@vger.kernel.org&gt; # 5.4
Acked-by: Lorenzo Bianconi &lt;lorenzo@kernel.org&gt;
Signed-off-by: Stephan Gerhold &lt;stephan@gerhold.net&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
At the moment, attempting to probe a device with ST_LSM6DS3_ID
(e.g. using the st,lsm6ds3 compatible) fails with:

    st_lsm6dsx_i2c 1-006b: unsupported whoami [69]

... even though 0x69 is the whoami listed for ST_LSM6DS3_ID.

This happens because st_lsm6dsx_check_whoami() also attempts
to match unspecified (zero-initialized) entries in the "id" array.
ST_LSM6DS3_ID = 0 will therefore match any entry in
st_lsm6dsx_sensor_settings (here: the first), because none of them
actually have all 12 entries listed in the "id" array.

Avoid this by additionally checking if "name" is set,
which is only set for valid entries in the "id" array.

Note: Although the problem was introduced earlier it did not surface until
commit 52f4b1f19679 ("iio: imu: st_lsm6dsx: add support for accel/gyro unit of lsm9ds1")
because ST_LSM6DS3_ID was the first entry in st_lsm6dsx_sensor_settings.

Fixes: d068e4a0f921 ("iio: imu: st_lsm6dsx: add support to multiple devices with the same settings")
Cc: &lt;stable@vger.kernel.org&gt; # 5.4
Acked-by: Lorenzo Bianconi &lt;lorenzo@kernel.org&gt;
Signed-off-by: Stephan Gerhold &lt;stephan@gerhold.net&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>iio: adc: ad7124: Fix DT channel configuration</title>
<updated>2020-01-13T11:08:14+00:00</updated>
<author>
<name>Alexandru Tachici</name>
<email>alexandru.tachici@analog.com</email>
</author>
<published>2019-12-20T10:07:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d7857e4ee1ba69732b16c73b2f2dde83ecd78ee4'/>
<id>d7857e4ee1ba69732b16c73b2f2dde83ecd78ee4</id>
<content type='text'>
This patch fixes device tree channel configuration.

ad7124 driver reads channels configuration from the device tree.
It expects to find channel specifications as child nodes.
Before this patch ad7124 driver assumed that the child nodes are parsed
by for_each_available_child_of_node in the order 0,1,2,3...

This is wrong and the real order of the children can be seen by running:
dtc -I fs /sys/firmware/devicetree/base on the machine.

For example, running this on an rpi 3B+ yields the real
children order: 4,2,0,7,5,3,1,6

Before this patch the driver assigned the channel configuration
like this:
        - 0 &lt;- 4
        - 1 &lt;- 2
        - 2 &lt;- 0
        ........
For example, the symptoms can be observed by connecting the 4th channel
to a 1V tension and then reading the in_voltage0-voltage19_raw sysfs
(multiplied of course by the scale) one would see that channel 0
measures 1V and channel 4 measures only noise.

Now the driver uses the reg property of each child in order to
correctly identify to which channel the parsed configuration
belongs to.

Fixes b3af341bbd966: ("iio: adc: Add ad7124 support")
Signed-off-by: Alexandru Tachici &lt;alexandru.tachici@analog.com&gt;
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch fixes device tree channel configuration.

ad7124 driver reads channels configuration from the device tree.
It expects to find channel specifications as child nodes.
Before this patch ad7124 driver assumed that the child nodes are parsed
by for_each_available_child_of_node in the order 0,1,2,3...

This is wrong and the real order of the children can be seen by running:
dtc -I fs /sys/firmware/devicetree/base on the machine.

For example, running this on an rpi 3B+ yields the real
children order: 4,2,0,7,5,3,1,6

Before this patch the driver assigned the channel configuration
like this:
        - 0 &lt;- 4
        - 1 &lt;- 2
        - 2 &lt;- 0
        ........
For example, the symptoms can be observed by connecting the 4th channel
to a 1V tension and then reading the in_voltage0-voltage19_raw sysfs
(multiplied of course by the scale) one would see that channel 0
measures 1V and channel 4 measures only noise.

Now the driver uses the reg property of each child in order to
correctly identify to which channel the parsed configuration
belongs to.

Fixes b3af341bbd966: ("iio: adc: Add ad7124 support")
Signed-off-by: Alexandru Tachici &lt;alexandru.tachici@analog.com&gt;
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'iio-fixes-for-5.5a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-linus</title>
<updated>2019-12-09T08:27:52+00:00</updated>
<author>
<name>Greg Kroah-Hartman</name>
<email>gregkh@linuxfoundation.org</email>
</author>
<published>2019-12-09T08:27:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7347f09a198a045d5f6ea5e9c8fcc1db98e5a854'/>
<id>7347f09a198a045d5f6ea5e9c8fcc1db98e5a854</id>
<content type='text'>
Jonathan writes:

First set of fixes for IIO in the 5.5 cycle.

Mixture of old things people have just hit, and a few late breaking
issues with things that went in during the merge window.

Being sent promptly to resolve potential DT breakage causing
issues for binding test builds.

* ad7606
  - Avoid reading extra data from the device over what was intended.
* ad7124
  - Enable the internal reference when in use.
* ad7292
  - Fix up license for newly added binding.  Better to not have this go
    out in a release with more limited header than intended.
  - Fix a constraint on number of channels.
* ad7949
  - Fix an issue which can result in readouts being from the wrong channel.
* hdc100x
  - Fix wrong ABI usage (units) for relative humidity channel.
* intel mrfld
  - Allocate right amount of private data (currently allocating too much).
* ltc2983
  - Avoid a potential issue with machine endianness and wrong length device
    tree read.
* max1027
  - Clean up leak of an iio_trigger on probe failure.
* max9611
  - Ensure we sleep long enough to successfully initialize the sensor.
* mpu6050
  - Fix wrong ABI usage (units) for temperature channel.
* st_accel
  - Fix an unused variable warning.
* st_lsm6dsx
  - Fix decimation factor issue that can lead to missaligned datasets
    (and hence garbage)
  - Fix an issue with how we track enabled fifo channels.
  - Avoid powering off the device if wake up events are enabled.

* tag 'iio-fixes-for-5.5a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio:
  iio: adc: max9611: Fix too short conversion time delay
  iio: ad7949: fix channels mixups
  iio: imu: st_lsm6dsx: do not power-off accel if events are enabled
  iio: imu: st_lsm6dsx: track hw FIFO buffering with fifo_mask
  iio: imu: st_lsm6dsx: fix decimation factor estimation
  iio: imu: inv_mpu6050: fix temperature reporting using bad unit
  iio: humidity: hdc100x: fix IIO_HUMIDITYRELATIVE channel reporting
  iio: adc: max1027: fix not unregistered iio trigger
  iio: adc: intel_mrfld_adc: Allocating too much data in probe()
  iio: adc: ad7124: Enable internal reference
  dt-bindings: iio: adc: ad7292: fix constraint over channel quantity
  dt-bindings: iio: adc: ad7292: Update SPDX identifier
  iio: temperature: ltc2983: fix u32 read into a unsigned long long
  iio: st_accel: Fix unused variable warning
  iio: adc: ad7606: fix reading unnecessary data from device
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Jonathan writes:

First set of fixes for IIO in the 5.5 cycle.

Mixture of old things people have just hit, and a few late breaking
issues with things that went in during the merge window.

Being sent promptly to resolve potential DT breakage causing
issues for binding test builds.

* ad7606
  - Avoid reading extra data from the device over what was intended.
* ad7124
  - Enable the internal reference when in use.
* ad7292
  - Fix up license for newly added binding.  Better to not have this go
    out in a release with more limited header than intended.
  - Fix a constraint on number of channels.
* ad7949
  - Fix an issue which can result in readouts being from the wrong channel.
* hdc100x
  - Fix wrong ABI usage (units) for relative humidity channel.
* intel mrfld
  - Allocate right amount of private data (currently allocating too much).
* ltc2983
  - Avoid a potential issue with machine endianness and wrong length device
    tree read.
* max1027
  - Clean up leak of an iio_trigger on probe failure.
* max9611
  - Ensure we sleep long enough to successfully initialize the sensor.
* mpu6050
  - Fix wrong ABI usage (units) for temperature channel.
* st_accel
  - Fix an unused variable warning.
* st_lsm6dsx
  - Fix decimation factor issue that can lead to missaligned datasets
    (and hence garbage)
  - Fix an issue with how we track enabled fifo channels.
  - Avoid powering off the device if wake up events are enabled.

* tag 'iio-fixes-for-5.5a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio:
  iio: adc: max9611: Fix too short conversion time delay
  iio: ad7949: fix channels mixups
  iio: imu: st_lsm6dsx: do not power-off accel if events are enabled
  iio: imu: st_lsm6dsx: track hw FIFO buffering with fifo_mask
  iio: imu: st_lsm6dsx: fix decimation factor estimation
  iio: imu: inv_mpu6050: fix temperature reporting using bad unit
  iio: humidity: hdc100x: fix IIO_HUMIDITYRELATIVE channel reporting
  iio: adc: max1027: fix not unregistered iio trigger
  iio: adc: intel_mrfld_adc: Allocating too much data in probe()
  iio: adc: ad7124: Enable internal reference
  dt-bindings: iio: adc: ad7292: fix constraint over channel quantity
  dt-bindings: iio: adc: ad7292: Update SPDX identifier
  iio: temperature: ltc2983: fix u32 read into a unsigned long long
  iio: st_accel: Fix unused variable warning
  iio: adc: ad7606: fix reading unnecessary data from device
</pre>
</div>
</content>
</entry>
<entry>
<title>iio: adc: max9611: Fix too short conversion time delay</title>
<updated>2019-12-08T18:10:30+00:00</updated>
<author>
<name>Geert Uytterhoeven</name>
<email>geert+renesas@glider.be</email>
</author>
<published>2019-12-02T08:55:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9fd229c478fbf77c41c8528aa757ef14210365f6'/>
<id>9fd229c478fbf77c41c8528aa757ef14210365f6</id>
<content type='text'>
As of commit b9ddd5091160793e ("iio: adc: max9611: Fix temperature
reading in probe"), max9611 initialization sometimes fails on the
Salvator-X(S) development board with:

    max9611 4-007f: Invalid value received from ADC 0x8000: aborting
    max9611: probe of 4-007f failed with error -5

The max9611 driver tests communications with the chip by reading the die
temperature during the probe function, which returns an invalid value.

According to the datasheet, the typical ADC conversion time is 2 ms, but
no minimum or maximum values are provided.  Maxim Technical Support
confirmed this was tested with temperature Ta=25 degreeC, and promised
to inform me if a maximum/minimum value is available (they didn't get
back to me, so I assume it is not).

However, the driver assumes a 1 ms conversion time.  Usually the
usleep_range() call returns after more than 1.8 ms, hence it succeeds.
When it returns earlier, the data register may be read too early, and
the previous measurement value will be returned.  After boot, this is
the temperature POR (power-on reset) value, causing the failure above.

Fix this by increasing the delay from 1000-2000 µs to 3000-3300 µs.

Note that this issue has always been present, but it was exposed by the
aformentioned commit.

Fixes: 69780a3bbc0b1e7e ("iio: adc: Add Maxim max9611 ADC driver")
Signed-off-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Reviewed-by: Jacopo Mondi &lt;jacopo+renesas@jmondi.org&gt;
Reviewed-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
As of commit b9ddd5091160793e ("iio: adc: max9611: Fix temperature
reading in probe"), max9611 initialization sometimes fails on the
Salvator-X(S) development board with:

    max9611 4-007f: Invalid value received from ADC 0x8000: aborting
    max9611: probe of 4-007f failed with error -5

The max9611 driver tests communications with the chip by reading the die
temperature during the probe function, which returns an invalid value.

According to the datasheet, the typical ADC conversion time is 2 ms, but
no minimum or maximum values are provided.  Maxim Technical Support
confirmed this was tested with temperature Ta=25 degreeC, and promised
to inform me if a maximum/minimum value is available (they didn't get
back to me, so I assume it is not).

However, the driver assumes a 1 ms conversion time.  Usually the
usleep_range() call returns after more than 1.8 ms, hence it succeeds.
When it returns earlier, the data register may be read too early, and
the previous measurement value will be returned.  After boot, this is
the temperature POR (power-on reset) value, causing the failure above.

Fix this by increasing the delay from 1000-2000 µs to 3000-3300 µs.

Note that this issue has always been present, but it was exposed by the
aformentioned commit.

Fixes: 69780a3bbc0b1e7e ("iio: adc: Add Maxim max9611 ADC driver")
Signed-off-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Reviewed-by: Jacopo Mondi &lt;jacopo+renesas@jmondi.org&gt;
Reviewed-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>iio: ad7949: fix channels mixups</title>
<updated>2019-12-08T18:10:30+00:00</updated>
<author>
<name>Andrea Merello</name>
<email>andrea.merello@gmail.com</email>
</author>
<published>2019-12-02T14:13:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3b71f6b59508b1c9befcb43de434866aafc76520'/>
<id>3b71f6b59508b1c9befcb43de434866aafc76520</id>
<content type='text'>
Each time we need to read a sample (from the sysfs interface, since the
driver supports only it) the driver writes the configuration register
with the proper settings needed to perform the said read, then it runs
another xfer to actually read the resulting value. Most notably the
configuration register is updated to set the ADC internal MUX depending by
which channel the read targets.

Unfortunately this seems not enough to ensure correct operation because
the ADC works in a pipelined-like fashion and the new configuration isn't
applied in time.

The ADC alternates two phases: acquisition and conversion. During the
acquisition phase the ADC samples the analog signal in an internal
capacitor; in the conversion phase the ADC performs the actual analog to
digital conversion of the stored voltage. Note that of course the MUX
needs to be set to the proper channel when the acquisition phase is
performed.

Once the conversion phase has been completed, the device automatically
switches back to a new acquisition; on the other hand the device switches
from acquisition to conversion on the rising edge of SPI cs signal (that
is when the xfer finishes).

Only after both two phases have been completed (with the proper settings
already written in the configuration register since the beginning) it is
possible to read the outcome from SPI bus.

With the current driver implementation, we end up in the following
situation:

        _______  1st xfer ____________  2nd xfer ___________________
SPI cs..       \_________/            \_________/
SPI rd.. idle  |(val N-2)+    idle    | val N-1 +   idle ...
SPI wr.. idle  |  cfg N  +    idle    |   (X)   +   idle ...
------------------------ + -------------------- + ------------------
  AD  ..   acq  N-1      + cnv N-1 |  acq N     +  cnv N  | acq N+1

As shown in the diagram above, the value we read in the Nth read belongs
to configuration setting N-1.

In case the configuration is not changed (config[N] == config[N-1]), then
we still get correct data, but in case the configuration changes (i.e.
switching the MUX on another channel), we get wrong data (data from the
previously selected channel).

This patch fixes this by performing one more "dummy" transfer in order to
ending up in reading the data when it's really ready, as per the following
timing diagram.

        _______  1st xfer ____________  2nd xfer ___________  3rd xfer ___
SPI cs..       \_________/            \_________/           \_________/
SPI rd.. idle  |(val N-2)+    idle    |(val N-1)+    idle   |  val N  + ..
SPI wr.. idle  |  cfg N  +    idle    |   (X)   +    idle   |   (X)   + ..
------------------------ + -------------------- + ------------------- + --
  AD  ..   acq  N-1      + cnv N-1 |  acq N     +  cnv N  | acq N+1   | ..

NOTE: in the latter case (cfg changes), the acquisition phase for the
value to be read begins after the 1st xfer, that is after the read request
has been issued on sysfs. On the other hand, if the cfg doesn't change,
then we can refer to the fist diagram assuming N == (N - 1); the
acquisition phase _begins_ before the 1st xfer (potentially a lot of time
before the read has been issued via sysfs, but it _ends_ after the 1st
xfer, that is _after_ the read has started. This should guarantee a
reasonably fresh data, which value represents the voltage that the sampled
signal has after the read start or maybe just around it.

Signed-off-by: Andrea Merello &lt;andrea.merello@gmail.com&gt;
Reviewed-by: Charles-Antoine Couret &lt;charles-antoine.couret@essensium.com&gt;
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Each time we need to read a sample (from the sysfs interface, since the
driver supports only it) the driver writes the configuration register
with the proper settings needed to perform the said read, then it runs
another xfer to actually read the resulting value. Most notably the
configuration register is updated to set the ADC internal MUX depending by
which channel the read targets.

Unfortunately this seems not enough to ensure correct operation because
the ADC works in a pipelined-like fashion and the new configuration isn't
applied in time.

The ADC alternates two phases: acquisition and conversion. During the
acquisition phase the ADC samples the analog signal in an internal
capacitor; in the conversion phase the ADC performs the actual analog to
digital conversion of the stored voltage. Note that of course the MUX
needs to be set to the proper channel when the acquisition phase is
performed.

Once the conversion phase has been completed, the device automatically
switches back to a new acquisition; on the other hand the device switches
from acquisition to conversion on the rising edge of SPI cs signal (that
is when the xfer finishes).

Only after both two phases have been completed (with the proper settings
already written in the configuration register since the beginning) it is
possible to read the outcome from SPI bus.

With the current driver implementation, we end up in the following
situation:

        _______  1st xfer ____________  2nd xfer ___________________
SPI cs..       \_________/            \_________/
SPI rd.. idle  |(val N-2)+    idle    | val N-1 +   idle ...
SPI wr.. idle  |  cfg N  +    idle    |   (X)   +   idle ...
------------------------ + -------------------- + ------------------
  AD  ..   acq  N-1      + cnv N-1 |  acq N     +  cnv N  | acq N+1

As shown in the diagram above, the value we read in the Nth read belongs
to configuration setting N-1.

In case the configuration is not changed (config[N] == config[N-1]), then
we still get correct data, but in case the configuration changes (i.e.
switching the MUX on another channel), we get wrong data (data from the
previously selected channel).

This patch fixes this by performing one more "dummy" transfer in order to
ending up in reading the data when it's really ready, as per the following
timing diagram.

        _______  1st xfer ____________  2nd xfer ___________  3rd xfer ___
SPI cs..       \_________/            \_________/           \_________/
SPI rd.. idle  |(val N-2)+    idle    |(val N-1)+    idle   |  val N  + ..
SPI wr.. idle  |  cfg N  +    idle    |   (X)   +    idle   |   (X)   + ..
------------------------ + -------------------- + ------------------- + --
  AD  ..   acq  N-1      + cnv N-1 |  acq N     +  cnv N  | acq N+1   | ..

NOTE: in the latter case (cfg changes), the acquisition phase for the
value to be read begins after the 1st xfer, that is after the read request
has been issued on sysfs. On the other hand, if the cfg doesn't change,
then we can refer to the fist diagram assuming N == (N - 1); the
acquisition phase _begins_ before the 1st xfer (potentially a lot of time
before the read has been issued via sysfs, but it _ends_ after the 1st
xfer, that is _after_ the read has started. This should guarantee a
reasonably fresh data, which value represents the voltage that the sampled
signal has after the read start or maybe just around it.

Signed-off-by: Andrea Merello &lt;andrea.merello@gmail.com&gt;
Reviewed-by: Charles-Antoine Couret &lt;charles-antoine.couret@essensium.com&gt;
Cc: &lt;Stable@vger.kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>iio: imu: st_lsm6dsx: do not power-off accel if events are enabled</title>
<updated>2019-12-08T18:10:30+00:00</updated>
<author>
<name>Lorenzo Bianconi</name>
<email>lorenzo@kernel.org</email>
</author>
<published>2019-11-29T09:37:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=bd41c445b7b96e46efb799ff33bdf870479488cf'/>
<id>bd41c445b7b96e46efb799ff33bdf870479488cf</id>
<content type='text'>
Do not power-off accel unconditionally if wake-up events are enabled
powering off the hw FIFO. At the same time do not power-off the accel
sensor if it is 'batched' in the hw FIFO disabling sensor events

Fixes: b5969abfa8b8 ("iio: imu: st_lsm6dsx: add motion events")
Tested-by: Sean Nyekjaer &lt;sean@geanix.com&gt;
Signed-off-by: Lorenzo Bianconi &lt;lorenzo@kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Do not power-off accel unconditionally if wake-up events are enabled
powering off the hw FIFO. At the same time do not power-off the accel
sensor if it is 'batched' in the hw FIFO disabling sensor events

Fixes: b5969abfa8b8 ("iio: imu: st_lsm6dsx: add motion events")
Tested-by: Sean Nyekjaer &lt;sean@geanix.com&gt;
Signed-off-by: Lorenzo Bianconi &lt;lorenzo@kernel.org&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>iio: imu: st_lsm6dsx: track hw FIFO buffering with fifo_mask</title>
<updated>2019-12-08T18:10:30+00:00</updated>
<author>
<name>Lorenzo Bianconi</name>
<email>lorenzo@kernel.org</email>
</author>
<published>2019-11-28T15:42:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c2686eb2aed322c642b5a291d5b9d67fe4301d4a'/>
<id>c2686eb2aed322c642b5a291d5b9d67fe4301d4a</id>
<content type='text'>
Track hw FIFO state introducing fifo_mask since now the accel sensor
can be enabled during suspend/resume in order to trigger the wake-up
enabling the FIFO in st_lsm6dsx_resume even if it was disabled before
the suspend.  Hence we must separately track the fifo state.

Fixes: 4c997dfa692d ("iio: imu: st_lsm6dsx: add wakeup-source option")
Signed-off-by: Lorenzo Bianconi &lt;lorenzo@kernel.org&gt;
Tested-by: Sean Nyekjaer &lt;sean@geanix.com&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Track hw FIFO state introducing fifo_mask since now the accel sensor
can be enabled during suspend/resume in order to trigger the wake-up
enabling the FIFO in st_lsm6dsx_resume even if it was disabled before
the suspend.  Hence we must separately track the fifo state.

Fixes: 4c997dfa692d ("iio: imu: st_lsm6dsx: add wakeup-source option")
Signed-off-by: Lorenzo Bianconi &lt;lorenzo@kernel.org&gt;
Tested-by: Sean Nyekjaer &lt;sean@geanix.com&gt;
Signed-off-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
