staging: comedi: dt9812: cleanup analog in subdevice (*insn_read)

For aesthetic reasons, rename the function to help with grepping and
rename some of the local vars.

dt9812_analog_in() can fail. Make sure to check for any failure and
return the errno.

The comedi core expects the (*insn_read) functions to return either
an errno or the number of samples read. Change the final return to
insn->n to make this clearer.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/dt9812.c b/drivers/staging/comedi/drivers/dt9812.c
index 7f6d43a..c83dc7f 100644 (file)
--- a/drivers/staging/comedi/drivers/dt9812.c
+++ b/drivers/staging/comedi/drivers/dt9812.c
@@ -631,20 +631,24 @@ static int dt9812_do_insn_bits(struct comedi_device *dev,
        return insn->n;
 }
 
-static int dt9812_ai_rinsn(struct comedi_device *dev,
-                          struct comedi_subdevice *s, struct comedi_insn *insn,
-                          unsigned int *data)
+static int dt9812_ai_insn_read(struct comedi_device *dev,
+                              struct comedi_subdevice *s,
+                              struct comedi_insn *insn,
+                              unsigned int *data)
 {
-       unsigned int channel = CR_CHAN(insn->chanspec);
-       int n;
-
-       for (n = 0; n < insn->n; n++) {
-               u16 value = 0;
+       unsigned int chan = CR_CHAN(insn->chanspec);
+       u16 val = 0;
+       int ret;
+       int i;
 
-               dt9812_analog_in(dev, channel, &value, DT9812_GAIN_1);
-               data[n] = value;
+       for (i = 0; i < insn->n; i++) {
+               ret = dt9812_analog_in(dev, chan, &val, DT9812_GAIN_1);
+               if (ret)
+                       return ret;
+               data[i] = val;
        }
-       return n;
+
+       return insn->n;
 }
 
 static int dt9812_ao_rinsn(struct comedi_device *dev,
@@ -845,7 +849,7 @@ static int dt9812_auto_attach(struct comedi_device *dev,
        s->n_chan       = 8;
        s->maxdata      = 0x0fff;
        s->range_table  = is_unipolar ? &range_unipolar2_5 : &range_bipolar10;
-       s->insn_read    = dt9812_ai_rinsn;
+       s->insn_read    = dt9812_ai_insn_read;
 
        /* Analog Output subdevice */
        s = &dev->subdevices[3];