staging: comedi: addi_apci_3120: use comedi_bytes_to_samples()

Use the helper function to calculate the number of samples in the DMA
buffer. For aesthetics, tidy up the local variables.

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>

drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c

@@ -12,20 +12,21 @@ static void apci3120_interrupt_dma(int irq, void *d)
 	struct comedi_async *async = s->async;
 	struct comedi_cmd *cmd = &async->cmd;
 	struct apci3120_dmabuf *dmabuf;
-	unsigned int samplesinbuf;
+	unsigned int nbytes;
+	unsigned int nsamples;
 
 	dmabuf = &devpriv->dmabuf[devpriv->cur_dmabuf];
 
-	samplesinbuf = dmabuf->use_size - inl(devpriv->amcc + AMCC_OP_REG_MWTC);
+	nbytes = dmabuf->use_size - inl(devpriv->amcc + AMCC_OP_REG_MWTC);
 
-	if (samplesinbuf < dmabuf->use_size)
+	if (nbytes < dmabuf->use_size)
 		dev_err(dev->class_dev, "Interrupted DMA transfer!\n");
-	if (samplesinbuf & 1) {
+	if (nbytes & 1) {
 		dev_err(dev->class_dev, "Odd count of bytes in DMA ring!\n");
 		async->events |= COMEDI_CB_ERROR;
 		return;
 	}
-	samplesinbuf = samplesinbuf >> 1;	/*  number of received samples */
+	nsamples = comedi_bytes_to_samples(s, nbytes);
 
 	if (devpriv->use_double_buffer) {
 		struct apci3120_dmabuf *next_dmabuf;
@@ -36,8 +37,8 @@ static void apci3120_interrupt_dma(int irq, void *d)
 		apci3120_init_dma(dev, next_dmabuf);
 	}
 
-	if (samplesinbuf) {
-		comedi_buf_write_samples(s, dmabuf->virt, samplesinbuf);
+	if (nsamples) {
+		comedi_buf_write_samples(s, dmabuf->virt, nsamples);
 
 		if (!(cmd->flags & CMDF_WAKE_EOS))
 			async->events |= COMEDI_CB_EOS;