On Sun, May 5, 2019 at 8:36 AM Jonathan Cameron <jic23@xxxxxxxxxxxxxxxxxxxxx> wrote: > > On Fri, 3 May 2019 12:54:46 +0200 > Fabien Lahoudere <fabien.lahoudere@xxxxxxxxxxxxx> wrote: > > > From: Gwendal Grignou <gwendal@xxxxxxxxxxxx> > > > > Version 3 of the EC protocol provides min and max frequencies and fifo > > size for EC sensors. > > The driver allows EC to set parameters for version 3 and set default values > > for earlier versions. > > The sysfs entries are read only and cannot be used to impact on values. > > > > Signed-off-by: Gwendal Grignou <gwendal@xxxxxxxxxxxx> > > Signed-off-by: Fabien Lahoudere <fabien.lahoudere@xxxxxxxxxxxxx> > Mostly changes in here will follow from comments on the cover letter > but a few other things inline. > > Thanks, > > Jonathan > > --- > > .../ABI/testing/sysfs-bus-iio-cros-ec | 24 ++++ > > .../cros_ec_sensors/cros_ec_sensors_core.c | 126 +++++++++++++++++- > > .../linux/iio/common/cros_ec_sensors_core.h | 7 + > > include/linux/mfd/cros_ec_commands.h | 21 +++ > > 4 files changed, 177 insertions(+), 1 deletion(-) > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-iio-cros-ec b/Documentation/ABI/testing/sysfs-bus-iio-cros-ec > > index 0e95c2ca105c..85d266f4a57e 100644 > > --- a/Documentation/ABI/testing/sysfs-bus-iio-cros-ec > > +++ b/Documentation/ABI/testing/sysfs-bus-iio-cros-ec > > @@ -26,3 +26,27 @@ Description: > > driver and represents the sensor ID as exposed by the EC. This > > ID is used by the Android sensor service hardware abstraction > > layer (sensor HAL) through the Android container on ChromeOS. > > + > > +What: /sys/bus/iio/devices/iio:deviceX/min_frequency > > +Date: April 2019 > > +KernelVersion: 5.0 > > +Contact: linux-iio@xxxxxxxxxxxxxxx > > +Description: > > + This attribute is exposed by CrOS EC sensors. It defines the > > + minimum frequency used by the sensor. > > + > > +What: /sys/bus/iio/devices/iio:deviceX/max_frequency > > +Date: April 2019 > > +KernelVersion: 5.0 > > +Contact: linux-iio@xxxxxxxxxxxxxxx > > +Description: > > + This attribute is exposed by CrOS EC sensors. It defines the > > + maximum frequency used by the sensor. > > + > See reply to the cover letter on these. Bonus points if you implement them > with the read_avail callback. > > > +What: /sys/bus/iio/devices/iio:deviceX/max_events > > +Date: April 2019 > > +KernelVersion: 5.0 > > +Contact: linux-iio@xxxxxxxxxxxxxxx > > +Description: > > + This attribute is exposed by CrOS EC sensors. It defines the > > + maximum number of events in the fifo. > > Why does userspace care? Is use to report the size of the hardware FIFO to Android, to enable batching mode: https://source.android.com/devices/sensors/batching. It is reported in fifoReservedEventCount or fifoMaxEventCount in the sensor_t structure described at https://source.android.com/devices/sensors/hal-interface#sensor_t. Having said that, batching is not terribly useful for tablet or laptop, but is critical for wearable.
