linux-stable.git/drivers/iio, branch v5.4.4

iio: ad7949: fix channels mixups

2019-12-17T18:56:45+00:00

[ Upstream commit 3b71f6b59508b1c9befcb43de434866aafc76520 ]

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 
Reviewed-by: Charles-Antoine Couret 
Cc: 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Sasha Levin

iio: ad7949: kill pointless "readback"-handling code

2019-12-17T18:56:45+00:00

[ Upstream commit c270bbf7bb9ddc4e2a51b3c56557c377c9ac79bc ]

The device could be configured to spit out also the configuration word
while reading the AD result value (in the same SPI xfer) - this is called
"readback" in the device datasheet.

The driver checks if readback is enabled and it eventually adjusts the SPI
xfer length and it applies proper shifts to still get the data, discarding
the configuration word.

The readback option is actually never enabled (the driver disables it), so
the said checks do not serve for any purpose.

Since enabling the readback option seems not to provide any advantage (the
driver entirely sets the configuration word without relying on any default
value), just kill the said, unused, code.

Signed-off-by: Andrea Merello 
Reviewed-by: Alexandru Ardelean 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Sasha Levin

iio: adc: ad7124: Enable internal reference

2019-12-17T18:55:44+00:00

commit 11d7c8d3b1259c303fb52789febed58f0bc35ad1 upstream.

When the internal reference was selected by a channel it was not enabled.
This patch fixes that and enables it.

Fixes: b3af341bbd96 ("iio: adc: Add ad7124 support")
Signed-off-by: Mircea Caprioru 
Cc: 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Greg Kroah-Hartman

iio: adc: ad7606: fix reading unnecessary data from device

2019-12-17T18:55:43+00:00

commit 341826a065660d1b77d89e6335b6095cd654271c upstream.

When a conversion result is being read from ADC, the driver reads the
number of channels + 1 because it thinks that IIO_CHAN_SOFT_TIMESTAMP
is also a physical channel. This patch fixes this issue.

Fixes: 2985a5d88455 ("staging: iio: adc: ad7606: Move out of staging")
Reported-by: Robert Wörle 
Signed-off-by: Beniamin Bia 
Cc: 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Greg Kroah-Hartman

iio: imu: inv_mpu6050: fix temperature reporting using bad unit

2019-12-17T18:55:42+00:00

commit 53eaa9c27fdc01b4f4d885223e29f97393409e7e upstream.

Temperature should be reported in milli-degrees, not degrees. Fix
scale and offset values to use the correct unit.

This is a fix for an issue that has been present for a long time.
The fixes tag reflects the point at which the code last changed in a
fashion that would make this fix patch no longer apply.  Backports
will be necessary to fix those elements that predate that patch.

Fixes: 1615fe41a195 ("iio: imu: mpu6050: Fix FIFO layout for ICM20602")
Cc: stable@vger.kernel.org
Signed-off-by: Jean-Baptiste Maneyrol 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Greg Kroah-Hartman

iio: humidity: hdc100x: fix IIO_HUMIDITYRELATIVE channel reporting

2019-12-17T18:55:42+00:00

commit 342a6928bd5017edbdae376042d8ad6af3d3b943 upstream.

The IIO_HUMIDITYRELATIVE channel was being incorrectly reported back
as percent when it should have been milli percent. This is via an
incorrect scale value being returned to userspace.

Signed-off-by: Chris Lesiak 
Acked-by: Matt Ranostay 
Cc: 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Greg Kroah-Hartman

iio: adis16480: Fix scales factors

2019-12-17T18:55:41+00:00

commit 49549cb23a2926eba70bb634e361daea0f319794 upstream.

This patch fixes the scales for the gyroscope, accelerometer and
barometer. The pressure scale was just wrong. For the others, the scale
factors were not taking into account that a 32bit word is being read
from the device.

Fixes: 7abad1063deb ("iio: adis16480: Fix scale factors")
Fixes: 82e7a1b25017 ("iio: imu: adis16480: Add support for ADIS1649x family of devices")
Signed-off-by: Nuno Sá 
Cc: 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Greg Kroah-Hartman

iio: imu: st_lsm6dsx: fix ODR check in st_lsm6dsx_write_raw

2019-12-17T18:55:40+00:00

commit fc3f6ad7f5dc6c899fbda0255865737bac88c2e0 upstream.

Since st_lsm6dsx i2c master controller relies on accel device as trigger
and slave devices can run at different ODRs we must select an accel_odr >=
slave_odr. Report real accel ODR in st_lsm6dsx_check_odr() in order to
properly set sensor frequency in st_lsm6dsx_write_raw and avoid to
report unsupported frequency

Fixes: 6ffb55e5009ff ("iio: imu: st_lsm6dsx: introduce ST_LSM6DSX_ID_EXT sensor ids")
Signed-off-by: Lorenzo Bianconi 
Cc: 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Greg Kroah-Hartman

iio: adis16480: Add debugfs_reg_access entry

2019-12-17T18:55:40+00:00

commit 4c35b7a51e2f291471f7221d112c6a45c63e83bc upstream.

The driver is defining debugfs entries by calling
`adis16480_debugfs_init()`. However, those entries are attached to the
iio_dev debugfs entry which won't exist if no debugfs_reg_access
callback is provided.

Fixes: 2f3abe6cbb6c ("iio:imu: Add support for the ADIS16480 and similar IMUs")
Signed-off-by: Nuno Sá 
Cc: 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Greg Kroah-Hartman

iio: adc: stm32-adc: fix stopping dma

2019-10-27T15:57:19+00:00

There maybe a race when using dmaengine_terminate_all(). The predisable
routine may call iio_triggered_buffer_predisable() prior to a pending DMA
callback.
Adopt dmaengine_terminate_sync() to ensure there's no pending DMA request
before calling iio_triggered_buffer_predisable().

Fixes: 2763ea0585c9 ("iio: adc: stm32: add optional dma support")

Signed-off-by: Fabrice Gasnier 
Cc: 
Signed-off-by: Jonathan Cameron