Commit 4a4c1b1d authored Oct 30, 2018 by Ian Abbott Committed by Greg Kroah-Hartman Nov 07, 2018

staging: comedi: ni_labpc_common: Use insn->n in AO insn_write handler



The `insn_write` handler for the AO subdevice (`labpc_ao_insn_write()`)
currently ignores `insn->n` (the number of samples to write) and assumes
a single sample is to be written.  But `insn->n` could be 0, meaning no
samples should be written, in which case `data[0]` is invalid.

Follow the usual Comedi guidelines and change `labpc_ao_insn_write()` to
write the specified number of samples.  This fixes the assumption that
`data[0]` is valid.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 43818b03

drivers/staging/comedi/drivers/ni_labpc_common.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -906,7 +906,9 @@ static int labpc_ao_insn_write(struct comedi_device *dev,
		{
		const struct labpc_boardinfo *board = dev->board_ptr;
		struct labpc_private *devpriv = dev->private;
		int channel, range;
		unsigned int channel;
		unsigned int range;
		unsigned int i;
		unsigned long flags;

		channel = CR_CHAN(insn->chanspec);
		@@ -932,9 +934,10 @@ static int labpc_ao_insn_write(struct comedi_device *dev,
		devpriv->write_byte(dev, devpriv->cmd6, CMD6_REG);
		}
		/* send data */
		labpc_ao_write(dev, s, channel, data[0]);
		for (i = 0; i < insn->n; i++)
		labpc_ao_write(dev, s, channel, data[i]);

		return 1;
		return insn->n;
		}

		/* lowlevel write to eeprom/dac */

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