[PATCH 3.13 50/99] staging: comedi: adv_pci1710: fix analog output readback value

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



3.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>

commit 1e85c1ea1ff2a60659e790ef8ec76c7339445841 upstream.

The last value written to a analog output channel is cached in the
private data of this driver for readback.

Currently, the wrong value is cached in the (*insn_write) functions.
The current code stores the data[n] value for readback afer the loop
has written all the values. At this time 'n' points past the end of
the data array.

Fix the functions by using a local variable to hold the data being
written to the analog output channel. This variable is then used
after the loop is complete to store the readback value. The current
value is retrieved before the loop in case no values are actually
written..

Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Ian Abbott <abbotti@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/staging/comedi/drivers/adv_pci1710.c |   17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

--- a/drivers/staging/comedi/drivers/adv_pci1710.c
+++ b/drivers/staging/comedi/drivers/adv_pci1710.c
@@ -489,6 +489,7 @@ static int pci171x_insn_write_ao(struct
 				 struct comedi_insn *insn, unsigned int *data)
 {
 	struct pci1710_private *devpriv = dev->private;
+	unsigned int val;
 	int n, chan, range, ofs;
 
 	chan = CR_CHAN(insn->chanspec);
@@ -504,11 +505,14 @@ static int pci171x_insn_write_ao(struct
 		outw(devpriv->da_ranges, dev->iobase + PCI171x_DAREF);
 		ofs = PCI171x_DA1;
 	}
+	val = devpriv->ao_data[chan];
 
-	for (n = 0; n < insn->n; n++)
-		outw(data[n], dev->iobase + ofs);
+	for (n = 0; n < insn->n; n++) {
+		val = data[n];
+		outw(val, dev->iobase + ofs);
+	}
 
-	devpriv->ao_data[chan] = data[n];
+	devpriv->ao_data[chan] = val;
 
 	return n;
 
@@ -674,6 +678,7 @@ static int pci1720_insn_write_ao(struct
 				 struct comedi_insn *insn, unsigned int *data)
 {
 	struct pci1710_private *devpriv = dev->private;
+	unsigned int val;
 	int n, rangereg, chan;
 
 	chan = CR_CHAN(insn->chanspec);
@@ -683,13 +688,15 @@ static int pci1720_insn_write_ao(struct
 		outb(rangereg, dev->iobase + PCI1720_RANGE);
 		devpriv->da_ranges = rangereg;
 	}
+	val = devpriv->ao_data[chan];
 
 	for (n = 0; n < insn->n; n++) {
-		outw(data[n], dev->iobase + PCI1720_DA0 + (chan << 1));
+		val = data[n];
+		outw(val, dev->iobase + PCI1720_DA0 + (chan << 1));
 		outb(0, dev->iobase + PCI1720_SYNCOUT);	/*  update outputs */
 	}
 
-	devpriv->ao_data[chan] = data[n];
+	devpriv->ao_data[chan] = val;
 
 	return n;
 }


--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]