Introduce a helper function to disable and the ISA DMA controller and
return the residue as described in Documentation/DMA-ISA-LPC.txt.
The DMA will always be disabled when labpc_setup_dma() is called. Remove
the unnecessary disable in that function.
Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
Cc: Ian Abbott <abbotti@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/drivers/ni_labpc_isadma.c | 41 ++++++++++++++----------
1 file changed, 24 insertions(+), 17 deletions(-)
diff --git a/drivers/staging/comedi/drivers/ni_labpc_isadma.c b/drivers/staging/comedi/drivers/ni_labpc_isadma.c
index 0ce8aad..862fb7e 100644
--- a/drivers/staging/comedi/drivers/ni_labpc_isadma.c
+++ b/drivers/staging/comedi/drivers/ni_labpc_isadma.c
@@ -31,6 +31,19 @@
/* size in bytes of dma buffer */
#define LABPC_ISADMA_BUFFER_SIZE 0xff00
+static unsigned int labpc_isadma_disable(struct labpc_dma_desc *dma)
+{
+ unsigned long flags;
+ unsigned int residue;
+
+ flags = claim_dma_lock();
+ disable_dma(dma->chan);
+ residue = get_dma_residue(dma->chan);
+ release_dma_lock(flags);
+
+ return residue;
+}
+
/* utility function that suggests a dma transfer size in bytes */
static unsigned int labpc_suggest_transfer_size(struct comedi_device *dev,
struct comedi_subdevice *s)
@@ -67,10 +80,10 @@ void labpc_setup_dma(struct comedi_device *dev, struct comedi_subdevice *s)
unsigned long irq_flags;
irq_flags = claim_dma_lock();
- disable_dma(dma->chan);
/* clear flip-flop to make sure 2-byte registers for
* count and address get set correctly */
clear_dma_ff(dma->chan);
+ set_dma_mode(dma->chan, DMA_MODE_READ);
set_dma_addr(dma->chan, dma->hw_addr);
/* set appropriate size of transfer */
dma->size = labpc_suggest_transfer_size(dev, s);
@@ -99,20 +112,16 @@ void labpc_drain_dma(struct comedi_device *dev)
status = devpriv->stat1;
- flags = claim_dma_lock();
- disable_dma(dma->chan);
- /* clear flip-flop to make sure 2-byte registers for
- * count and address get set correctly */
- clear_dma_ff(dma->chan);
-
- /* figure out how many points to read */
- max_points = dma->size / sample_size;
- /* residue is the number of points left to be done on the dma
+ /*
+ * residue is the number of bytes left to be done on the dma
* transfer. It should always be zero at this point unless
* the stop_src is set to external triggering.
*/
- residue = get_dma_residue(dma->chan) / sample_size;
- num_points = max_points - residue;
+ 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;
@@ -132,6 +141,8 @@ void labpc_drain_dma(struct comedi_device *dev)
devpriv->count -= num_points;
/* 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);
release_dma_lock(flags);
@@ -170,7 +181,6 @@ void labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
{
struct labpc_private *devpriv = dev->private;
struct labpc_dma_desc *dma = &devpriv->dma_desc;
- unsigned long dma_flags;
if (dma_chan != 1 && dma_chan != 3)
return;
@@ -187,10 +197,7 @@ void labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
dma->chan = dma_chan;
- dma_flags = claim_dma_lock();
- disable_dma(dma->chan);
- set_dma_mode(dma->chan, DMA_MODE_READ);
- release_dma_lock(dma_flags);
+ labpc_isadma_disable(dma);
}
EXPORT_SYMBOL_GPL(labpc_init_dma_chan);
--
2.0.3
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