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staging: comedi: ni_pcidio: Mark buffer for writing when setting up DMA.

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When setting up the DMA for 'read' streaming acquisition on the DIO
subdevice, mark the whole buffer as writable before starting the DMA.
This prevents a spurious detection of a DMA overwrite of good data
during the first interrupt.

Problem reported by Nicholas Nell.  Fix suggested by Frank Mori Hess.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2012-01-09 15:47:30 +00:00 committed by Greg Kroah-Hartman
parent 9e77e6b62e
commit 41add2e84b
1 changed files with 3 additions and 0 deletions
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3
drivers/staging/comedi/drivers/ni_pcidio.c
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@ -1012,6 +1012,9 @@ static int setup_mite_dma(struct comedi_device *dev, struct comedi_subdevice *s)
devpriv->di_mite_chan->dir = COMEDI_INPUT;
/* write alloc the entire buffer */
comedi_buf_write_alloc(s->async, s->async->prealloc_bufsz);
mite_prep_dma(devpriv->di_mite_chan, 32, 32);
mite_dma_arm(devpriv->di_mite_chan);