staging: comedi: dt282x: introduce dt282x_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/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c
index 2d01c6cfbb4d9aa6ca2ad42de51bd51e160bdf8e..54c679a0387b14606041e5dfb7051ab661bd546f 100644 (file)
--- a/drivers/staging/comedi/drivers/dt282x.c
+++ b/drivers/staging/comedi/drivers/dt282x.c
@@ -339,6 +339,15 @@ static void dt282x_isadma_program(struct dt282x_dma_desc *dma)
        release_dma_lock(flags);
 }
 
+static void dt282x_isadma_disable(struct dt282x_dma_desc *dma)
+{
+       unsigned long flags;
+
+       flags = claim_dma_lock();
+       disable_dma(dma->chan);
+       release_dma_lock(flags);
+}
+
 static int dt282x_prep_ai_dma(struct comedi_device *dev, int dma_index, int n)
 {
        struct dt282x_private *devpriv = dev->private;
@@ -377,9 +386,10 @@ static int dt282x_prep_ao_dma(struct comedi_device *dev, int dma_index, int n)
 static void dt282x_disable_dma(struct comedi_device *dev)
 {
        struct dt282x_private *devpriv = dev->private;
+       int i;
 
-       disable_dma(devpriv->dma_desc[0].chan);
-       disable_dma(devpriv->dma_desc[1].chan);
+       for (i = 0; i < 2; i++)
+               dt282x_isadma_disable(&devpriv->dma_desc[i]);
 }
 
 static unsigned int dt282x_ns_to_timer(unsigned int *ns, unsigned int flags)
@@ -463,7 +473,7 @@ static void dt282x_ao_dma_interrupt(struct comedi_device *dev,
        outw(devpriv->supcsr | DT2821_SUPCSR_CLRDMADNE,
             dev->iobase + DT2821_SUPCSR_REG);
 
-       disable_dma(dma->chan);
+       dt282x_isadma_disable(dma);
 
        if (!dt282x_ao_setup_dma(dev, s, devpriv->cur_dma))
                s->async->events |= COMEDI_CB_OVERFLOW;
@@ -482,7 +492,7 @@ static void dt282x_ai_dma_interrupt(struct comedi_device *dev,
        outw(devpriv->supcsr | DT2821_SUPCSR_CLRDMADNE,
             dev->iobase + DT2821_SUPCSR_REG);
 
-       disable_dma(dma->chan);
+       dt282x_isadma_disable(dma);
 
        dt282x_munge(dev, s, dma->virt_addr, dma->size);
        ret = comedi_buf_write_samples(s, dma->virt_addr, nsamples);