staging: comedi: mite: pass subdevice to mite_buf_change()

`mite_buf_change()` in the "mite" module currently takes a pointer to a
`struct comedi_async` and gets a pointer to the owning `struct
comedi_subdevice` from the `subdevice` member.  Change it to take a
pointer to a `struct comedi_subdevice` and use the `async` member.

The motivation for this is to eliminate the `subdevice` member of
`struct comedi_async`.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/mite.c

@@ -307,8 +307,9 @@ EXPORT_SYMBOL_GPL(mite_dma_arm);
 /**************************************/
 
 int mite_buf_change(struct mite_dma_descriptor_ring *ring,
-		    struct comedi_async *async)
+		    struct comedi_subdevice *s)
 {
+	struct comedi_async *async = s->async;
 	unsigned int n_links;
 	int i;
 
@@ -333,7 +334,7 @@ int mite_buf_change(struct mite_dma_descriptor_ring *ring,
 			       n_links * sizeof(struct mite_dma_descriptor),
 			       &ring->descriptors_dma_addr, GFP_KERNEL);
 	if (!ring->descriptors) {
-		dev_err(async->subdevice->device->class_dev,
+		dev_err(s->device->class_dev,
 			"mite: ring buffer allocation failed\n");
 		return -ENOMEM;
 	}

drivers/staging/comedi/drivers/mite.h

@@ -120,7 +120,7 @@ int mite_done(struct mite_channel *mite_chan);
 void mite_prep_dma(struct mite_channel *mite_chan,
 		   unsigned int num_device_bits, unsigned int num_memory_bits);
 int mite_buf_change(struct mite_dma_descriptor_ring *ring,
-		    struct comedi_async *async);
+		    struct comedi_subdevice *s);
 
 static inline int CHAN_OFFSET(int channel)
 {

drivers/staging/comedi/drivers/ni_660x.c

@@ -836,7 +836,7 @@ static int ni_660x_buf_change(struct comedi_device *dev,
 	struct ni_gpct *counter = s->private;
 	int ret;
 
-	ret = mite_buf_change(mite_ring(devpriv, counter), s->async);
+	ret = mite_buf_change(mite_ring(devpriv, counter), s);
 	if (ret < 0)
 		return ret;
 

drivers/staging/comedi/drivers/ni_pcidio.c

@@ -806,7 +806,7 @@ static int ni_pcidio_change(struct comedi_device *dev,
 	struct nidio96_private *devpriv = dev->private;
 	int ret;
 
-	ret = mite_buf_change(devpriv->di_mite_ring, s->async);
+	ret = mite_buf_change(devpriv->di_mite_ring, s);
 	if (ret < 0)
 		return ret;
 

drivers/staging/comedi/drivers/ni_pcimio.c

@@ -1560,7 +1560,7 @@ static int pcimio_ai_change(struct comedi_device *dev,
 	struct ni_private *devpriv = dev->private;
 	int ret;
 
-	ret = mite_buf_change(devpriv->ai_mite_ring, s->async);
+	ret = mite_buf_change(devpriv->ai_mite_ring, s);
 	if (ret < 0)
 		return ret;
 
@@ -1573,7 +1573,7 @@ static int pcimio_ao_change(struct comedi_device *dev,
 	struct ni_private *devpriv = dev->private;
 	int ret;
 
-	ret = mite_buf_change(devpriv->ao_mite_ring, s->async);
+	ret = mite_buf_change(devpriv->ao_mite_ring, s);
 	if (ret < 0)
 		return ret;
 
@@ -1587,7 +1587,7 @@ static int pcimio_gpct0_change(struct comedi_device *dev,
 	struct ni_private *devpriv = dev->private;
 	int ret;
 
-	ret = mite_buf_change(devpriv->gpct_mite_ring[0], s->async);
+	ret = mite_buf_change(devpriv->gpct_mite_ring[0], s);
 	if (ret < 0)
 		return ret;
 
@@ -1601,7 +1601,7 @@ static int pcimio_gpct1_change(struct comedi_device *dev,
 	struct ni_private *devpriv = dev->private;
 	int ret;
 
-	ret = mite_buf_change(devpriv->gpct_mite_ring[1], s->async);
+	ret = mite_buf_change(devpriv->gpct_mite_ring[1], s);
 	if (ret < 0)
 		return ret;
 
@@ -1614,7 +1614,7 @@ static int pcimio_dio_change(struct comedi_device *dev,
 	struct ni_private *devpriv = dev->private;
 	int ret;
 
-	ret = mite_buf_change(devpriv->cdo_mite_ring, s->async);
+	ret = mite_buf_change(devpriv->cdo_mite_ring, s);
 	if (ret < 0)
 		return ret;