staging: comedi: pcl812: introduce pcl812_isadma_disable()

According to Documentation/DMA-ISA-LPC.txt, the DMA lock needs to be
claimed before using any of the ISA DMA routines. Introduce a helper
function to disable the ISA DMA controller and add the necessary
locking calls.

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 6b38147cf2aef84e2c17154e3fe44032c59f9f2a..c67c2c70c0de96f107b735779f289877d7579fb4 100644 (file)
--- a/drivers/staging/comedi/drivers/pcl812.c
+++ b/drivers/staging/comedi/drivers/pcl812.c
@@ -547,6 +547,15 @@ static void pcl812_isadma_program(unsigned int dma_chan,
        release_dma_lock(flags);
 }
 
+static void pcl812_isadma_disable(unsigned int dma_chan)
+{
+       unsigned long flags;
+
+       flags = claim_dma_lock();
+       disable_dma(dma_chan);
+       release_dma_lock(flags);
+}
+
 static void pcl812_start_pacer(struct comedi_device *dev, bool load_timers)
 {
        struct pcl812_private *devpriv = dev->private;
@@ -618,7 +627,7 @@ static void pcl812_ai_setup_next_dma(struct comedi_device *dev,
        struct pcl812_private *devpriv = dev->private;
        struct pcl812_dma_desc *dma;
 
-       disable_dma(devpriv->dma);
+       pcl812_isadma_disable(devpriv->dma);
 
        devpriv->cur_dma = 1 - devpriv->cur_dma;
        dma = &devpriv->dma_desc[devpriv->cur_dma];
@@ -980,7 +989,7 @@ static int pcl812_ai_cancel(struct comedi_device *dev,
        struct pcl812_private *devpriv = dev->private;
 
        if (devpriv->ai_dma)
-               disable_dma(devpriv->dma);
+               pcl812_isadma_disable(devpriv->dma);
 
        outb(devpriv->mode_reg_int | PCL812_CTRL_DISABLE_TRIG,
             dev->iobase + PCL812_CTRL_REG);