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

`mite_sync_output_dma()` 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

@@ -559,9 +559,9 @@ int mite_sync_input_dma(struct mite_channel *mite_chan,
 EXPORT_SYMBOL_GPL(mite_sync_input_dma);
 
 int mite_sync_output_dma(struct mite_channel *mite_chan,
-			 struct comedi_async *async)
+			 struct comedi_subdevice *s)
 {
-	struct comedi_subdevice *s = async->subdevice;
+	struct comedi_async *async = s->async;
 	int count;
 	u32 nbytes_ub, nbytes_lb;
 	unsigned int old_alloc_count;
@@ -579,8 +579,7 @@ int mite_sync_output_dma(struct mite_channel *mite_chan,
 	    (int)(nbytes_ub - stop_count) > 0)
 		nbytes_ub = stop_count;
 	if ((int)(nbytes_ub - old_alloc_count) > 0) {
-		dev_warn(async->subdevice->device->class_dev,
-			 "mite: DMA underrun\n");
+		dev_warn(s->device->class_dev, "mite: DMA underrun\n");
 		async->events |= COMEDI_CB_OVERFLOW;
 		return -1;
 	}

drivers/staging/comedi/drivers/mite.h

@@ -108,7 +108,7 @@ void mite_dma_disarm(struct mite_channel *mite_chan);
 int mite_sync_input_dma(struct mite_channel *mite_chan,
 			struct comedi_subdevice *s);
 int mite_sync_output_dma(struct mite_channel *mite_chan,
-			 struct comedi_async *async);
+			 struct comedi_subdevice *s);
 u32 mite_bytes_written_to_memory_lb(struct mite_channel *mite_chan);
 u32 mite_bytes_written_to_memory_ub(struct mite_channel *mite_chan);
 u32 mite_bytes_read_from_memory_lb(struct mite_channel *mite_chan);

drivers/staging/comedi/drivers/ni_mio_common.c

@@ -877,7 +877,7 @@ static void mite_handle_b_linkc(struct mite_struct *mite,
 
 	spin_lock_irqsave(&devpriv->mite_channel_lock, flags);
 	if (devpriv->ao_mite_chan)
-		mite_sync_output_dma(devpriv->ao_mite_chan, s->async);
+		mite_sync_output_dma(devpriv->ao_mite_chan, s);
 	spin_unlock_irqrestore(&devpriv->mite_channel_lock, flags);
 }
 
@@ -3640,7 +3640,7 @@ static void handle_cdio_interrupt(struct comedi_device *dev)
 			       devpriv->mite->mite_io_addr +
 			       MITE_CHOR(devpriv->cdo_mite_chan->channel));
 		}
-		mite_sync_output_dma(devpriv->cdo_mite_chan, s->async);
+		mite_sync_output_dma(devpriv->cdo_mite_chan, s);
 	}
 	spin_unlock_irqrestore(&devpriv->mite_channel_lock, flags);
 #endif