staging: comedi: usbduxsigma: cleanup the private data 'outBuffer'

This buffer is used to cache the analog output values that are written
to the analog output channels. Currently it only caches the single
writes to the channels using the (*insn_write) callback. The async
command writes are not cached. The buffer is also being kzalloc'ed
during the attach of the driver to a size much larger that required.

Rename the CamelCase buffer and change it to an array in the private
data of the correct size to cache the analog output channel values.

Modify the analog output urb callback so it updates the cached values
with those used for the asynchronous command to allow readback after
the command completes.
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>

drivers/staging/comedi/drivers/usbduxsigma.c

@@ -98,6 +98,8 @@ Status: testing
 /* Number of channels (16 AD and offset)*/
 #define NUMCHANNELS 16
 
+#define USBDUXSIGMA_NUM_AO_CHAN		4
+
 /* Size of one A/D value */
 #define SIZEADIN          ((sizeof(int32_t)))
 
@@ -174,8 +176,8 @@ struct usbduxsigma_private {
 	int32_t *inBuffer;
 	/* input buffer for single insn */
 	int8_t *insnBuffer;
-	/* output buffer for single DA outputs */
-	int16_t *outBuffer;
+
+	unsigned int ao_readback[USBDUXSIGMA_NUM_AO_CHAN];
 
 	unsigned high_speed:1;
 	unsigned ai_cmd_running:1;
@@ -435,11 +437,9 @@ static void usbduxsub_ao_IsocIrq(struct urb *urb)
 		len = s->async->cmd.chanlist_len;
 		*datap++ = len;
 		for (i = 0; i < len; i++) {
+			unsigned int chan = devpriv->dac_commands[i];
 			short val;
 
-			if (i >= NUMOUTCHANNELS)
-				break;
-
 			ret = comedi_buf_get(s->async, &val);
 			if (ret < 0) {
 				dev_err(dev->class_dev, "buffer underflow\n");
@@ -447,7 +447,8 @@ static void usbduxsub_ao_IsocIrq(struct urb *urb)
 						     COMEDI_CB_OVERFLOW);
 			}
 			*datap++ = val;
-			*datap++ = devpriv->dac_commands[i];
+			*datap++ = chan;
+			devpriv->ao_readback[chan] = val;
 
 			s->async->events |= COMEDI_CB_BLOCK;
 			comedi_event(dev, s);
@@ -864,7 +865,7 @@ static int usbduxsigma_ao_insn_read(struct comedi_device *dev,
 
 	down(&devpriv->sem);
 	for (i = 0; i < insn->n; i++)
-		data[i] = devpriv->outBuffer[chan];
+		data[i] = devpriv->ao_readback[chan];
 	up(&devpriv->sem);
 
 	return insn->n;
@@ -895,7 +896,7 @@ static int usbduxsigma_ao_insn_write(struct comedi_device *dev,
 			up(&devpriv->sem);
 			return ret;
 		}
-		devpriv->outBuffer[chan] = data[i];
+		devpriv->ao_readback[chan] = data[i];
 	}
 	up(&devpriv->sem);
 
@@ -1462,8 +1463,8 @@ static int usbduxsigma_attach_common(struct comedi_device *dev)
 	dev->write_subdev = s;
 	s->type		= COMEDI_SUBD_AO;
 	s->subdev_flags	= SDF_WRITABLE | SDF_GROUND | SDF_CMD_WRITE;
-	s->n_chan	= 4;
-	s->len_chanlist	= 4;
+	s->n_chan	= USBDUXSIGMA_NUM_AO_CHAN;
+	s->len_chanlist	= s->n_chan;
 	s->maxdata	= 0x00ff;
 	s->range_table	= &range_unipolar2_5;
 	s->insn_write	= usbduxsigma_ao_insn_write;
@@ -1589,14 +1590,13 @@ static int usbduxsigma_alloc_usb_buffers(struct comedi_device *dev)
 	devpriv->dux_commands = kzalloc(SIZEOFDUXBUFFER, GFP_KERNEL);
 	devpriv->inBuffer = kzalloc(SIZEINBUF, GFP_KERNEL);
 	devpriv->insnBuffer = kzalloc(SIZEINSNBUF, GFP_KERNEL);
-	devpriv->outBuffer = kzalloc(SIZEOUTBUF, GFP_KERNEL);
 	devpriv->urbIn = kcalloc(devpriv->numOfInBuffers, sizeof(*urb),
 				 GFP_KERNEL);
 	devpriv->urbOut = kcalloc(devpriv->numOfOutBuffers, sizeof(*urb),
 				  GFP_KERNEL);
 	if (!devpriv->dac_commands || !devpriv->dux_commands ||
 	    !devpriv->inBuffer || !devpriv->insnBuffer ||
-	    !devpriv->outBuffer || !devpriv->urbIn || !devpriv->urbOut)
+	    !devpriv->urbIn || !devpriv->urbOut)
 		return -ENOMEM;
 
 	for (i = 0; i < devpriv->numOfInBuffers; i++) {
@@ -1701,7 +1701,6 @@ static void usbduxsigma_free_usb_buffers(struct comedi_device *dev)
 		}
 		kfree(devpriv->urbIn);
 	}
-	kfree(devpriv->outBuffer);
 	kfree(devpriv->insnBuffer);
 	kfree(devpriv->inBuffer);
 	kfree(devpriv->dux_commands);