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  1. 29 Mar, 2015 3 commits
    • Octavian Purdila's avatar
      iio: bmc150_accel: add support for hardware fifo · 3bbec977
      Octavian Purdila authored 
      We only advertise hardware fifo support if the I2C bus supports full
I2C or smbus I2C block data reads since it is mandatory to read the
full frame in one read (otherwise the rest of the frame is discarded).

The hardware fifo is enabled only when triggers are not active because:

(a) when using the any-motion trigger the user expects to see samples
based on ROC events, but the fifo stores samples based on the sample
frequency

(b) the data-ready trigger is waking the CPU for for every sample, so
using the hardware fifo does not have any benefit
Signed-off-by: default avatarOctavian Purdila <octavian.purdila@intel.com>
Reviewed-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      3bbec977
    • Octavian Purdila's avatar
      iio: add support for hardware fifo · f4f4673b
      Octavian Purdila authored 
      Some devices have hardware buffers that can store a number of samples
for later consumption. Hardware usually provides interrupts to notify
the processor when the FIFO is full or when it has reached a certain
watermark level. This helps with reducing the number of interrupts to
the host processor and thus it helps decreasing the power consumption.

This patch enables usage of hardware FIFOs for IIO devices in
conjunction with software device buffers. When the hardware FIFO is
enabled the samples are stored in the hardware FIFO. The samples are
later flushed to the device software buffer when the number of entries
in the hardware FIFO reaches the hardware watermark or when a flush
operation is triggered by the user when doing a non-blocking read
on an empty software device buffer.

In order to implement hardware FIFO support the device drivers must
implement the following new operations: setting and getting the
hardware FIFO watermark level, flushing the hardware FIFO to the
software device buffer. The device must also expose information about
the hardware FIFO such it's minimum and maximum watermark and if
necessary a list of supported watermark values. Finally, the device
driver must activate the hardware FIFO when the device buffer is
enabled, if the current device settings allows it.

The software device buffer watermark is passed by the IIO core to the
device driver as a hint for the hardware FIFO watermark. The device
driver can adjust this value to allow for hardware limitations (such
as capping it to the maximum hardware watermark or adjust it to a
value that is supported by the hardware). It can also disable the
hardware watermark (and implicitly the hardware FIFO) it this value is
below the minimum hardware watermark.

Since a driver may support hardware FIFO only when not in triggered
buffer mode (due to different semantics of hardware FIFO sampling and
triggered sampling) this patch changes the IIO core code to allow
falling back to non-triggered buffered mode if no trigger is enabled.
Signed-off-by: default avatarOctavian Purdila <octavian.purdila@intel.com>
Reviewed-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      f4f4673b
    • Josselin Costanzi's avatar
      iio: add watermark logic to iio read and poll · 37d34556
      Josselin Costanzi authored 
      Currently the IIO buffer blocking read only wait until at least one
data element is available.
This patch makes the reader sleep until enough data is collected before
returning to userspace. This should limit the read() calls count when
trying to get data in batches.

Co-author: Yannick Bedhomme <yannick.bedhomme@mobile-devices.fr>
Signed-off-by: default avatarJosselin Costanzi <josselin.costanzi@mobile-devices.fr>
[rebased and remove buffer timeout]
Signed-off-by: default avatarOctavian Purdila <octavian.purdila@intel.com>
Reviewed-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      37d34556
  3. 28 Mar, 2015 7 commits
  5. 24 Mar, 2015 28 commits
  7. 23 Mar, 2015 2 commits
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