staging: comedi: pcl818: use common function to setup dma

THe pcl818_ai_setup_dma() and pcl818_ai_setup_next_dma() functions are similar
other than the buffer switch and the inclusion of the "unread_samples" in
pcl818_ai_setup_next_dma() when calculating the dma size.

Merge these two functions by initializing the 'dma->cur_dma' in the callers
and passing '0' for the "unread_samples" when first starting the 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/pcl818.c b/drivers/staging/comedi/drivers/pcl818.c
index fa7b4e22953f7006e08b727cb4c655810270e314..ba2e1373f43d4fcfab1fd5ea549ce1f5e9eac7ec 100644 (file)
--- a/drivers/staging/comedi/drivers/pcl818.c
+++ b/drivers/staging/comedi/drivers/pcl818.c
@@ -332,49 +332,22 @@ static void pcl818_start_pacer(struct comedi_device *dev, bool load_counters)
 }
 
 static void pcl818_ai_setup_dma(struct comedi_device *dev,
-                               struct comedi_subdevice *s)
-{
-       struct pcl818_private *devpriv = dev->private;
-       struct comedi_isadma *dma = devpriv->dma;
-       struct comedi_isadma_desc *desc = &dma->desc[0];
-       unsigned int nsamples;
-
-       comedi_isadma_disable(dma->chan);
-
-       dma->cur_dma = 0;
-
-       /*
-        * Determine dma size based on the buffer maxsize and the number of
-        * samples remaining in the command.
-        */
-       nsamples = comedi_bytes_to_samples(s, desc->maxsize);
-       nsamples = comedi_nsamples_left(s, nsamples);
-       desc->size = comedi_samples_to_bytes(s, nsamples);
-       comedi_isadma_program(desc);
-}
-
-static void pcl818_ai_setup_next_dma(struct comedi_device *dev,
-                                    struct comedi_subdevice *s,
-                                    unsigned int unread_samples)
+                               struct comedi_subdevice *s,
+                               unsigned int unread_samples)
 {
        struct pcl818_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
-       struct comedi_isadma_desc *desc;
-       unsigned int max_samples;
+       struct comedi_isadma_desc *desc = &dma->desc[dma->cur_dma];
+       unsigned int max_samples = comedi_bytes_to_samples(s, desc->maxsize);
        unsigned int nsamples;
 
        comedi_isadma_disable(dma->chan);
 
-       dma->cur_dma = 1 - dma->cur_dma;
-       desc = &dma->desc[dma->cur_dma];
-
        /*
         * Determine dma size based on the buffer maxsize plus the number of
         * unread samples and the number of samples remaining in the command.
         */
-       max_samples = comedi_bytes_to_samples(s, desc->maxsize);
-       nsamples = max_samples + unread_samples;
-       nsamples = comedi_nsamples_left(s, nsamples);
+       nsamples = comedi_nsamples_left(s, max_samples + unread_samples);
        if (nsamples > unread_samples) {
                nsamples -= unread_samples;
                desc->size = comedi_samples_to_bytes(s, nsamples);
@@ -554,7 +527,9 @@ static void pcl818_handle_dma(struct comedi_device *dev,
        unsigned int val;
        int i;
 
-       pcl818_ai_setup_next_dma(dev, s, nsamples);
+       /* restart dma with the next buffer */
+       dma->cur_dma = 1 - dma->cur_dma;
+       pcl818_ai_setup_dma(dev, s, nsamples);
 
        for (i = 0; i < nsamples; i++) {
                val = ptr[i];
@@ -790,6 +765,7 @@ static int pcl818_ai_cmd(struct comedi_device *dev,
                         struct comedi_subdevice *s)
 {
        struct pcl818_private *devpriv = dev->private;
+       struct comedi_isadma *dma = devpriv->dma;
        struct comedi_cmd *cmd = &s->async->cmd;
        unsigned int ctrl = 0;
        unsigned int seglen;
@@ -815,8 +791,10 @@ static int pcl818_ai_cmd(struct comedi_device *dev,
 
        outb(PCL818_CNTENABLE_PACER_ENA, dev->iobase + PCL818_CNTENABLE_REG);
 
-       if (devpriv->dma) {
-               pcl818_ai_setup_dma(dev, s);
+       if (dma) {
+               /* setup and enable dma for the first buffer */
+               dma->cur_dma = 0;
+               pcl818_ai_setup_dma(dev, s, 0);
 
                ctrl |= PCL818_CTRL_INTE | PCL818_CTRL_IRQ(dev->irq) |
                        PCL818_CTRL_DMAE;