From 72ba5c1612f5ea7f907290903e8fc24ed94aec13 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Tue, 13 Jan 2015 10:16:40 -0700 Subject: [PATCH] staging: comedi: ni_labpc_isadma: tidy up labpc_drain_dma() 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 Reviewed-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/ni_labpc_isadma.c | 48 ++++++++++++------------ 1 file changed, 24 insertions(+), 24 deletions(-) diff --git a/drivers/staging/comedi/drivers/ni_labpc_isadma.c b/drivers/staging/comedi/drivers/ni_labpc_isadma.c index 862fb7e..2fb7e72 100644 --- a/drivers/staging/comedi/drivers/ni_labpc_isadma.c +++ b/drivers/staging/comedi/drivers/ni_labpc_isadma.c @@ -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); -- 2.7.4