iio: buffer: ensure repeat alignment is a power of two

Use roundup_pow_of_two() in the calculation of iio_storage_bytes_for_si()
when scan_type->repeat > 1 to ensure that the size is a power of two.
storagebits is always going to be a power of two bytes, so we only need
to apply this to the repeat factor. The storage size is also used for
alignment, and we want to ensure that all alignments are a power of two.

The only repeat in use in the kernel currently is for quaternions, which
have a repeat of 4, so this does not change the result for existing
users.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index d59ab57dc994292ee91b0dcaadcaaff4dc9e5065..252ce4a6f913cdb83846872e1eab93cf1540d58a 100644 (file)
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -750,7 +750,7 @@ static int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
        bytes = scan_type->storagebits / 8;
 
        if (scan_type->repeat > 1)
-               bytes *= scan_type->repeat;
+               bytes *= roundup_pow_of_two(scan_type->repeat);
 
        return bytes;
 }