staging: comedi: pcl816: clarify dma channel request in pcl816_attach()

All the board types can do DMA using DMA channels 3 or 1. Remove the 'DMAbits',
which is a mask of the valid channels, from the boardinfo.

Refactor pcl816_attach() to remove the need for the goto.

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/pcl816.c b/drivers/staging/comedi/drivers/pcl816.c
index 5af687a..e67d24a 100644 (file)
--- a/drivers/staging/comedi/drivers/pcl816.c
+++ b/drivers/staging/comedi/drivers/pcl816.c
@@ -100,7 +100,6 @@ struct pcl816_board {
        int n_dochan;
        const struct comedi_lrange *ai_range_type;
        unsigned int IRQbits;
-       unsigned int DMAbits;
        int ai_maxdata;
        int ao_maxdata;
        int ai_chanlist;
@@ -118,7 +117,6 @@ static const struct pcl816_board boardtypes[] = {
                .n_dochan       = 16,
                .ai_range_type  = &range_pcl816,
                .IRQbits        = 0x00fc,
-               .DMAbits        = 0x0a,
                .ai_maxdata     = 0xffff,
                .ao_maxdata     = 0xffff,
                .ai_chanlist    = 1024,
@@ -133,7 +131,6 @@ static const struct pcl816_board boardtypes[] = {
                .n_dochan       = 16,
                .ai_range_type  = &range_pcl816,
                .IRQbits        = 0x00fc,
-               .DMAbits        = 0x0a,
                .ai_maxdata     = 0x3fff,
                .ao_maxdata     = 0x3fff,
                .ai_chanlist    = 1024,
@@ -866,7 +863,6 @@ static int pcl816_attach(struct comedi_device *dev, struct comedi_devconfig *it)
        const struct pcl816_board *board = comedi_board(dev);
        struct pcl816_private *devpriv;
        int ret;
-       unsigned int dma;
        unsigned long pages;
        /* int i; */
        struct comedi_subdevice *s;
@@ -894,30 +890,17 @@ static int pcl816_attach(struct comedi_device *dev, struct comedi_devconfig *it)
        devpriv->irq_blocked = 0;       /* number of subdevice which use IRQ */
        devpriv->int816_mode = 0;       /* mode of irq */
 
-       /* grab our DMA */
-       dma = 0;
-       devpriv->dma = dma;
-       if (!dev->irq)
-               goto no_dma;    /* if we haven't IRQ, we can't use DMA */
-
-       if (board->DMAbits != 0) {      /* board support DMA */
-               dma = it->options[2];
-               if (dma < 1)
-                       goto no_dma;    /* DMA disabled */
-
-               if (((1 << dma) & board->DMAbits) == 0) {
-                       dev_err(dev->class_dev,
-                               "DMA is out of allowed range, FAIL!\n");
-                       return -EINVAL; /* Bad DMA */
-               }
-               ret = request_dma(dma, dev->board_name);
+       /* we need an IRQ to do DMA on channel 3 or 1 */
+       if (dev->irq && (it->options[2] == 3 || it->options[2] == 1)) {
+               ret = request_dma(it->options[2], dev->board_name);
                if (ret) {
                        dev_err(dev->class_dev,
-                               "unable to allocate DMA %u, FAIL!\n", dma);
-                       return -EBUSY;  /* DMA isn't free */
+                               "unable to request DMA channel %d\n",
+                               it->options[2]);
+                       return -EBUSY;
                }
+               devpriv->dma = it->options[2];
 
-               devpriv->dma = dma;
                pages = 2;      /* we need 16KB */
                devpriv->dmabuf[0] = __get_dma_pages(GFP_KERNEL, pages);
 
@@ -945,8 +928,6 @@ static int pcl816_attach(struct comedi_device *dev, struct comedi_devconfig *it)
                devpriv->hwdmasize[1] = (1 << pages) * PAGE_SIZE;
        }
 
-no_dma:
-
 /*  if (board->n_aochan > 0)
     subdevs[1] = COMEDI_SUBD_AO;
   if (board->n_dichan > 0)