On 9/27/23 15:27, Andy Shevchenko wrote:
On Wed, Sep 27, 2023 at 11:26:07AM +0300, Matti Vaittinen wrote:
The iio_generic_buffer can return garbage values when the total size of
scan data is not a multiple of the largest element in the scan. This can be
demonstrated by reading a scan, consisting, for example of one 4-byte and
one 2-byte element, where the 4-byte element is first in the buffer.
The IIO generic buffer code does not take into account the last two
padding bytes that are needed to ensure that the 4-byte data for next
scan is correctly aligned.
Add the padding bytes required to align the next sample with the scan size.
...
+ /*
+ * We wan't the data in next sample to also be properly aligned so
Pardon me, won't or want, I didn't get?..
Both :D Well, purpose was to say want, but as I try to explain we get
what we want only in some case - in other cases we won't ;) Anyways,
this is something that should be fixed - thanks :)
+ * we'll add padding at the end if needed.
+ *
+ * Please note, this code does ensure alignment to maximum channel
+ * size. It works only as long as the channel sizes are 1, 2, 4 or 8
+ * bytes. Also, on 32 bit platforms it might be enough to align also
32-bit
+ * the 8 byte elements to 4 byte boundary - which this code is not
8-byte
4-byte
+ * doing.
+ */
Thanks!
Yours,
-- Matti
--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland
~~ When things go utterly wrong vim users can always type :help! ~~
