staging: comedi: pcl816: fix short DMA transactions

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When the cmd->stop_src == TRIG_COUNT the last DMA transfer might be smaller
than the buffer size. This results in invalid data being added to the async
buffer.

Add a 'size' member to the DMA descriptor and initialize it with the
actual size of the DMA transfer. Use that in interrupt and ai subdevice
(*poll) function to return the proper number of samples. Use the
comedi_bytes_to_samples() helper to convert the byte size to comedi
samples in the interrupt handler.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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H Hartley Sweeten 2015-01-12 10:56:04 -07:00 • committed by Greg Kroah-Hartman

parent a2c3966d18

commit ceb41be712

1 changed files with 18 additions and 16 deletions

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drivers/staging/comedi/drivers/pcl816.c

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