[PATCH 13/66] staging: comedi: pcl816: interrupt handlers should not busywait

H Hartley Sweeten hsweeten at visionengravers.com
Fri Feb 28 23:24:02 UTC 2014


The interrupt is only generated by the hardware at the completion of
an A/D conversion. Because of this the sanity check to make sure that
the A/D conversion is complete and data is available is probably
unnecessary but it doesn't hurt anything.

The busywait loop is a different issue. Interrupt routines should not
busywait. That's just mean...

Remove the bustwait and use pcl816_ai_eoc() to check for the end-of-
conversion.

Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>
Cc: Ian Abbott <abbotti at mev.co.uk>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/comedi/drivers/pcl816.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/drivers/staging/comedi/drivers/pcl816.c b/drivers/staging/comedi/drivers/pcl816.c
index 66d3c5a..6000ca91 100644
--- a/drivers/staging/comedi/drivers/pcl816.c
+++ b/drivers/staging/comedi/drivers/pcl816.c
@@ -279,22 +279,14 @@ static irqreturn_t interrupt_pcl816_ai_mode13_int(int irq, void *d)
 	struct pcl816_private *devpriv = dev->private;
 	struct comedi_subdevice *s = dev->read_subdev;
 	struct comedi_cmd *cmd = &s->async->cmd;
-	int timeout = 50;	/* wait max 50us */
 
-	while (timeout--) {
-		if (!(inb(dev->iobase + PCL816_STATUS) &
-		      PCL816_STATUS_DRDY_MASK))
-			break;
-		udelay(1);
-	}
-	if (!timeout) {		/*  timeout, bail error */
+	if (pcl816_ai_eoc(dev, s, NULL, 0)) {
 		outb(0, dev->iobase + PCL816_CLRINT);	/* clear INT request */
 		comedi_error(dev, "A/D mode1/3 IRQ without DRDY!");
 		s->cancel(dev, s);
 		s->async->events |= COMEDI_CB_EOA | COMEDI_CB_ERROR;
 		comedi_event(dev, s);
 		return IRQ_HANDLED;
-
 	}
 
 	comedi_buf_put(s->async, pcl816_ai_get_sample(dev, s));
-- 
1.8.5.2



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