staging: comedi: pcl812: use common function to setup dma

The pcl812_ai_setup_dma() and pcl812_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/pcl812.c b/drivers/staging/comedi/drivers/pcl812.c
index f6fe7d35fde2d6550455c5a1748807973c05686c..f76601aad785d2dd2af6ed5b296f05ae82f8da83 100644 (file)
--- a/drivers/staging/comedi/drivers/pcl812.c
+++ b/drivers/staging/comedi/drivers/pcl812.c
@@ -538,47 +538,27 @@ static void pcl812_start_pacer(struct comedi_device *dev, bool load_timers)
 }
 
 static void pcl812_ai_setup_dma(struct comedi_device *dev,
-                               struct comedi_subdevice *s)
-{
-       struct pcl812_private *devpriv = dev->private;
-       struct comedi_isadma *dma = devpriv->dma;
-       struct comedi_isadma_desc *desc = &dma->desc[0];
-       unsigned int bytes;
-       unsigned int nsamples;
-
-       dma->cur_dma = 0;
-
-       /* if using EOS, adapt DMA buffer to one scan */
-       bytes = devpriv->ai_eos ? comedi_bytes_per_scan(s) : desc->maxsize;
-
-       nsamples = comedi_bytes_to_samples(s, bytes);
-       nsamples = comedi_nsamples_left(s, nsamples);
-       desc->size = comedi_samples_to_bytes(s, nsamples);
-       comedi_isadma_program(desc);
-}
-
-static void pcl812_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 pcl812_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
-       struct comedi_isadma_desc *desc;
+       struct comedi_isadma_desc *desc = &dma->desc[dma->cur_dma];
        unsigned int bytes;
        unsigned int max_samples;
        unsigned int nsamples;
 
        comedi_isadma_disable(dma->chan);
 
-       dma->cur_dma = 1 - dma->cur_dma;
-       desc = &dma->desc[dma->cur_dma];
-
        /* if using EOS, adapt DMA buffer to one scan */
        bytes = devpriv->ai_eos ? comedi_bytes_per_scan(s) : desc->maxsize;
-
        max_samples = comedi_bytes_to_samples(s, bytes);
-       nsamples = max_samples + unread_samples;
-       nsamples = comedi_nsamples_left(s, nsamples);
+
+       /*
+        * Determine dma size based on the buffer size plus the number of
+        * unread samples and the number of samples remaining in the command.
+        */
+       nsamples = comedi_nsamples_left(s, max_samples + unread_samples);
        if (nsamples > max_samples) {
                nsamples -= max_samples;
                desc->size = comedi_samples_to_bytes(s, nsamples);
@@ -740,6 +720,7 @@ static int pcl812_ai_cmdtest(struct comedi_device *dev,
 static int pcl812_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 {
        struct pcl812_private *devpriv = dev->private;
+       struct comedi_isadma *dma = devpriv->dma;
        struct comedi_cmd *cmd = &s->async->cmd;
        unsigned int ctrl = 0;
        unsigned int i;
@@ -748,7 +729,7 @@ static int pcl812_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 
        pcl812_ai_set_chan_range(dev, cmd->chanlist[0], 1);
 
-       if (devpriv->dma) {     /*  check if we can use DMA transfer */
+       if (dma) {      /*  check if we can use DMA transfer */
                devpriv->ai_dma = 1;
                for (i = 1; i < cmd->chanlist_len; i++)
                        if (cmd->chanlist[0] != cmd->chanlist[i]) {
@@ -771,8 +752,11 @@ static int pcl812_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
                        devpriv->ai_dma = 0;
        }
 
-       if (devpriv->ai_dma)
-               pcl812_ai_setup_dma(dev, s);
+       if (devpriv->ai_dma) {
+               /* setup and enable dma for the first buffer */
+               dma->cur_dma = 0;
+               pcl812_ai_setup_dma(dev, s, 0);
+       }
 
        switch (cmd->convert_src) {
        case TRIG_TIMER:
@@ -859,7 +843,9 @@ static void pcl812_handle_dma(struct comedi_device *dev,
        bufptr = devpriv->ai_poll_ptr;
        devpriv->ai_poll_ptr = 0;
 
-       pcl812_ai_setup_next_dma(dev, s, nsamples);
+       /* restart dma with the next buffer */
+       dma->cur_dma = 1 - dma->cur_dma;
+       pcl812_ai_setup_dma(dev, s, nsamples);
 
        transfer_from_dma_buf(dev, s, desc->virt_addr, bufptr, nsamples);
 }