staging: comedi: cb_pcidas64: use comedi_async 'scans_done' to detect AO EOA

Remove the private data member 'ao_count' and use the comedi_async 'scans_done'
member to detect the analog output end-of-acquisition.

Use the comedi_nsamples_left() helper to get the number of samples to actually
read from the async buffer.
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/cb_pcidas64.c

@@ -1085,8 +1085,6 @@ struct pcidas64_private {
 	dma_addr_t ao_dma_desc_bus_addr;
 	/*  keeps track of buffer where the next ao sample should go */
 	unsigned int ao_dma_index;
-	/*  number of analog output samples remaining */
-	unsigned long ao_count;
 	unsigned int hw_revision;	/*  stc chip hardware revision number */
 	/*  last bits sent to INTR_ENABLE_REG register */
 	unsigned int intr_enable_bits;
@@ -2848,22 +2846,6 @@ static int last_ao_dma_load_completed(struct comedi_device *dev)
 	return 1;
 }
 
-static int ao_stopped_by_error(struct comedi_device *dev,
-			       const struct comedi_cmd *cmd)
-{
-	struct pcidas64_private *devpriv = dev->private;
-
-	if (cmd->stop_src == TRIG_NONE)
-		return 1;
-	if (cmd->stop_src == TRIG_COUNT) {
-		if (devpriv->ao_count)
-			return 1;
-		if (last_ao_dma_load_completed(dev) == 0)
-			return 1;
-	}
-	return 0;
-}
-
 static inline int ao_dma_needs_restart(struct comedi_device *dev,
 				       unsigned short dma_status)
 {
@@ -2894,20 +2876,13 @@ static unsigned int cb_pcidas64_ao_fill_buffer(struct comedi_device *dev,
 					       unsigned short *dest,
 					       unsigned int max_bytes)
 {
-	struct pcidas64_private *devpriv = dev->private;
-	struct comedi_cmd *cmd = &s->async->cmd;
 	unsigned int nsamples = comedi_bytes_to_samples(s, max_bytes);
 	unsigned int actual_bytes;
 
-	if (cmd->stop_src == TRIG_COUNT && devpriv->ao_count < nsamples)
-		nsamples = devpriv->ao_count;
-
+	nsamples = comedi_nsamples_left(s, nsamples);
 	actual_bytes = comedi_buf_read_samples(s, dest, nsamples);
-	nsamples = comedi_bytes_to_samples(s, actual_bytes);
-	if (cmd->stop_src == TRIG_COUNT)
-		devpriv->ao_count -= nsamples;
 
-	return nsamples;
+	return comedi_bytes_to_samples(s, actual_bytes);
 }
 
 static unsigned int load_ao_dma_buffer(struct comedi_device *dev,
@@ -3006,8 +2981,11 @@ static void handle_ao_interrupt(struct comedi_device *dev,
 	}
 
 	if ((status & DAC_DONE_BIT)) {
+		if ((cmd->stop_src == TRIG_COUNT &&
+		     async->scans_done >= cmd->stop_arg) ||
+		    last_ao_dma_load_completed(dev))
 			async->events |= COMEDI_CB_EOA;
-		if (ao_stopped_by_error(dev, cmd))
+		else
 			async->events |= COMEDI_CB_ERROR;
 	}
 	comedi_handle_events(dev, s);
@@ -3202,7 +3180,8 @@ static int prep_ao_dma(struct comedi_device *dev, const struct comedi_cmd *cmd)
 		       devpriv->main_iobase + DAC_FIFO_REG);
 	}
 
-	if (cmd->stop_src == TRIG_COUNT && devpriv->ao_count == 0)
+	if (cmd->stop_src == TRIG_COUNT &&
+	    s->async->scans_done >= cmd->stop_arg)
 		return 0;
 
 	nbytes = load_ao_dma_buffer(dev, cmd);
@@ -3267,7 +3246,6 @@ static int ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 	writew(0x0, devpriv->main_iobase + DAC_CONTROL0_REG);
 
 	devpriv->ao_dma_index = 0;
-	devpriv->ao_count = cmd->stop_arg * cmd->chanlist_len;
 
 	set_dac_select_reg(dev, cmd);
 	set_dac_interval_regs(dev, cmd);