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[RFC,0/4] IIO: Alignment fixes part 4 - bounce buffers for the hard cases.

Message ID 20210501172515.513486-1-jic23@kernel.org (mailing list archive)
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Series IIO: Alignment fixes part 4 - bounce buffers for the hard cases. | expand

Message

Jonathan Cameron May 1, 2021, 5:25 p.m. UTC 
From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

I finally got around to do a manual audit of all the calls to
iio_push_to_buffers_with_timestamp() which has the somewhat odd requirements
of:
1. 8 byte alignment of the provided buffer.
2. space for an 8 byte naturally aligned timestamp to be inserted at the
   end.

Unfortunately there were rather a lot of these left, but time to bite the bullet
and clean them up.

As discussed previous in
https://lore.kernel.org/linux-iio/20200920112742.170751-1-jic23@kernel.org/
it is not easy to fix the alignment issue without requiring a bounce buffer.
This final part of the 4 sets of fixes is concerned with the cases where
bounce buffers are the proposed solutions.

In these cases we have hardware that reads a prefix that we wish to
drop. That makes it hard to directly read the data into the correct location.

Rather than implementing bouce buffers in each case, this set provides some
magic in the core to handle them via a new function.
iio_push_to_buffers_with_ts_na() - non aligned

Note this is totally untested as I don't have suitable hardware or emulation.
I can fake something up in the dummy driver or via QEMU but I definitely want
both eyes and testing on this series!

Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Nuno Sa <nuno.sa@analog.com>

Jonathan Cameron (4):
  iio: core: Introduce iio_push_to_buffers_with_ts_na() for non aligned
    case.
  iio: adc: ti-adc108s102: Fix alignment of buffer pushed to iio
    buffers.
  iio: gyro: mpu3050: Fix alignment and size issues with buffers.
  iio: imu: adis16400: Fix buffer alignment requirements.

 drivers/iio/adc/ti-adc108s102.c   | 11 +++++-----
 drivers/iio/gyro/mpu3050-core.c   | 24 ++++++++++-----------
 drivers/iio/imu/adis16400.c       | 20 ++++++++++++-----
 drivers/iio/industrialio-buffer.c | 36 +++++++++++++++++++++++++++++++
 include/linux/iio/buffer.h        |  4 ++++
 include/linux/iio/iio-opaque.h    |  4 ++++
 6 files changed, 76 insertions(+), 23 deletions(-)