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staging: comedi: ni_labpc_isadma: tidy up labpc_drain_dma()

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Tidy up the code that determines the number of samples to read for the
current DMA transfer and how many samples are needed for the next DMA,

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>
This commit is contained in:
H Hartley Sweeten 2015-01-13 10:16:40 -07:00 committed by Greg Kroah-Hartman
parent 0f02b081da
commit 72ba5c1612
1 changed files with 24 additions and 24 deletions
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48
drivers/staging/comedi/drivers/ni_labpc_isadma.c
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@ -105,12 +105,11 @@ void labpc_drain_dma(struct comedi_device *dev)
struct comedi_subdevice *s = dev->read_subdev;
struct comedi_async *async = s->async;
struct comedi_cmd *cmd = &async->cmd;
unsigned int sample_size = comedi_bytes_per_sample(s);
int status;
unsigned int max_samples = comedi_bytes_to_samples(s, dma->size);
unsigned int residue;
unsigned int nsamples;
unsigned int leftover;
unsigned long flags;
unsigned int max_points, num_points, residue, leftover;
status = devpriv->stat1;
/*
* residue is the number of bytes left to be done on the dma
@ -119,32 +118,33 @@ void labpc_drain_dma(struct comedi_device *dev)
*/
residue = labpc_isadma_disable(dma);
/* figure out how many points to read */
max_points = dma->size / sample_size;
num_points = max_points - comedi_bytes_to_samples(s, residue);
if (cmd->stop_src == TRIG_COUNT && devpriv->count < num_points)
num_points = devpriv->count;
/* figure out how many points will be stored next time */
leftover = 0;
if (cmd->stop_src != TRIG_COUNT) {
leftover = dma->size / sample_size;
} else if (devpriv->count > num_points) {
leftover = devpriv->count - num_points;
if (leftover > max_points)
leftover = max_points;
/*
* Figure out how many samples to read for this transfer and
* how many will be stored for next time.
*/
nsamples = max_samples - comedi_bytes_to_samples(s, residue);
if (cmd->stop_src == TRIG_COUNT) {
if (devpriv->count <= nsamples) {
nsamples = devpriv->count;
leftover = 0;
} else {
leftover = devpriv->count - nsamples;
if (leftover > max_samples)
leftover = max_samples;
}
devpriv->count -= nsamples;
} else {
leftover = max_samples;
}
dma->size = comedi_samples_to_bytes(s, leftover);
comedi_buf_write_samples(s, dma->virt_addr, num_points);
if (cmd->stop_src == TRIG_COUNT)
devpriv->count -= num_points;
comedi_buf_write_samples(s, dma->virt_addr, nsamples);
/* set address and count for next transfer */
flags = claim_dma_lock();
set_dma_mode(dma->chan, DMA_MODE_READ);
set_dma_addr(dma->chan, dma->hw_addr);
set_dma_count(dma->chan, leftover * sample_size);
set_dma_count(dma->chan, dma->size);
release_dma_lock(flags);
}
EXPORT_SYMBOL_GPL(labpc_drain_dma);