staging: comedi: dt282x: IRQ and DMA are needed for async command support

This driver requires an IRQ and 2 DMA channels in order to execute async
commands.

Modify the (*attach) so that command support is only hooked up if
DMA is available. This allows removing the extra checks in the
command support functions.

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/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c
index 5ae15bcccb5e46b387ddb2dd22000b95fed6ea6d..cb12cca0f28f6ed1bdc5f8f42e65e39e234ef6e5 100644 (file)
--- a/drivers/staging/comedi/drivers/dt282x.c
+++ b/drivers/staging/comedi/drivers/dt282x.c
@@ -343,7 +343,6 @@ struct dt282x_private {
                int size;       /* size of current transfer */
        } dma[2];
        int dma_maxsize;        /* max size of DMA transfer (in bytes) */
-       int usedma;             /* driver uses DMA              */
        int current_dma_index;
        int dma_dir;
 };
@@ -412,10 +411,8 @@ static void dt282x_disable_dma(struct comedi_device *dev)
 {
        struct dt282x_private *devpriv = dev->private;
 
-       if (devpriv->usedma) {
-               disable_dma(devpriv->dma[0].chan);
-               disable_dma(devpriv->dma[1].chan);
-       }
+       disable_dma(devpriv->dma[0].chan);
+       disable_dma(devpriv->dma[1].chan);
 }
 
 static int dt282x_ns_to_timer(int *nanosec, int round_mode)
@@ -788,13 +785,6 @@ static int dt282x_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
        int timer;
        int ret;
 
-       if (devpriv->usedma == 0) {
-               comedi_error(dev,
-                            "driver requires 2 dma channels"
-                                               " to execute command");
-               return -EIO;
-       }
-
        dt282x_disable_dma(dev);
 
        if (cmd->convert_arg < board->ai_speed)
@@ -1014,13 +1004,6 @@ static int dt282x_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
        int timer;
        struct comedi_cmd *cmd = &s->async->cmd;
 
-       if (devpriv->usedma == 0) {
-               comedi_error(dev,
-                            "driver requires 2 dma channels"
-                                               " to execute command");
-               return -EIO;
-       }
-
        dt282x_disable_dma(dev);
 
        devpriv->supcsr = DT2821_ERRINTEN | DT2821_DS1 | DT2821_DDMA;
@@ -1155,21 +1138,6 @@ static int dt282x_grab_dma(struct comedi_device *dev, int dma1, int dma2)
        struct dt282x_private *devpriv = dev->private;
        int ret;
 
-       devpriv->usedma = 0;
-
-       if (!dma1 && !dma2)
-               return 0;
-
-       if (dma1 == dma2 || dma1 < 5 || dma2 < 5 || dma1 > 7 || dma2 > 7)
-               return -EINVAL;
-
-       if (dma2 < dma1) {
-               int i;
-               i = dma1;
-               dma1 = dma2;
-               dma2 = i;
-       }
-
        ret = request_dma(dma1, "dt282x A");
        if (ret)
                return -EBUSY;
@@ -1186,11 +1154,27 @@ static int dt282x_grab_dma(struct comedi_device *dev, int dma1, int dma2)
        if (!devpriv->dma[0].buf || !devpriv->dma[1].buf)
                return -ENOMEM;
 
-       devpriv->usedma = 1;
-
        return 0;
 }
 
+static void dt282x_free_dma(struct comedi_device *dev)
+{
+       struct dt282x_private *devpriv = dev->private;
+       int i;
+
+       if (!devpriv)
+               return;
+
+       for (i = 0; i < 2; i++) {
+               if (devpriv->dma[i].chan)
+                       free_dma(devpriv->dma[i].chan);
+               if (devpriv->dma[i].buf)
+                       free_page((unsigned long)devpriv->dma[i].buf);
+               devpriv->dma[i].chan = 0;
+               devpriv->dma[i].buf = NULL;
+       }
+}
+
 /*
    options:
    0   i/o base
@@ -1235,22 +1219,41 @@ static int dt282x_attach(struct comedi_device *dev, struct comedi_devconfig *it)
        }
        /* should do board test */
 
-       if (it->options[opt_irq] > 0) {
-               ret = request_irq(it->options[opt_irq], dt282x_interrupt, 0,
-                                 dev->board_name, dev);
-               if (ret == 0)
-                       dev->irq = it->options[opt_irq];
-       }
-
        devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
        if (!devpriv)
                return -ENOMEM;
 
-       if (dev->irq) {
-               ret = dt282x_grab_dma(dev, it->options[opt_dma1],
-                                     it->options[opt_dma2]);
-               if (ret < 0)
-                       return ret;
+       /* an IRQ and 2 DMA channels are required for async command support */
+       if (it->options[opt_irq] &&
+           it->options[opt_dma1] && it->options[opt_dma2]) {
+               unsigned int irq = it->options[opt_irq];
+               unsigned int dma1 = it->options[opt_dma1];
+               unsigned int dma2 = it->options[opt_dma2];
+
+               if (dma2 < dma1) {
+                       unsigned int swap;
+
+                       swap = dma1;
+                       dma1 = dma2;
+                       dma2 = swap;
+               }
+
+               if (dma1 != dma2 &&
+                   dma1 >= 5 && dma1 <= 7 &&
+                   dma2 >= 5 && dma2 <= 7) {
+                       ret = request_irq(irq, dt282x_interrupt, 0,
+                                         dev->board_name, dev);
+                       if (ret == 0) {
+                               dev->irq = irq;
+
+                               ret = dt282x_grab_dma(dev, dma1, dma2);
+                               if (ret < 0) {
+                                       dt282x_free_dma(dev);
+                                       free_irq(dev->irq, dev);
+                                       dev->irq = 0;
+                               }
+                       }
+               }
        }
 
        ret = comedi_alloc_subdevices(dev, 3);
@@ -1323,18 +1326,7 @@ static int dt282x_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 
 static void dt282x_detach(struct comedi_device *dev)
 {
-       struct dt282x_private *devpriv = dev->private;
-
-       if (dev->private) {
-               if (devpriv->dma[0].chan)
-                       free_dma(devpriv->dma[0].chan);
-               if (devpriv->dma[1].chan)
-                       free_dma(devpriv->dma[1].chan);
-               if (devpriv->dma[0].buf)
-                       free_page((unsigned long)devpriv->dma[0].buf);
-               if (devpriv->dma[1].buf)
-                       free_page((unsigned long)devpriv->dma[1].buf);
-       }
+       dt282x_free_dma(dev);
        comedi_legacy_detach(dev);
 }