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

diff --git a/drivers/staging/comedi/drivers/ni_labpc_isadma.c b/drivers/staging/comedi/drivers/ni_labpc_isadma.c
index 862fb7edb33d3b22ae0236c053562bd9c2014fb4..2fb7e728049b3d103521481c543ef3759867e3ae 100644 (file)
--- 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);