From fe57d1e113fcaf6af600c4d10168513c05230160 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Tue, 19 Mar 2019 16:54:41 +0000 Subject: staging: comedi: ni_mio_common: Use insn->n in ni_calib_insn_write() The `insn_write` handler for the calibration subdevice (`ni_calib_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. Change `ni_calib_insn_write()` to only write to the calibration device if `insn->n > 0`. There isn't much point writing all the values when `insn->n > 1`, so just write the last one (`data[insn->n - 1]`). Also follow the usual Comedi convention and return `insn->n` from the handler to indicate success (although any non-negative return value will do as far as the Comedi core is concerned). Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/ni_mio_common.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'drivers/staging/comedi') diff --git a/drivers/staging/comedi/drivers/ni_mio_common.c b/drivers/staging/comedi/drivers/ni_mio_common.c index 5edf59ac6706..613b6b2abf7d 100644 --- a/drivers/staging/comedi/drivers/ni_mio_common.c +++ b/drivers/staging/comedi/drivers/ni_mio_common.c @@ -4394,9 +4394,13 @@ static int ni_calib_insn_write(struct comedi_device *dev, struct comedi_insn *insn, unsigned int *data) { - ni_write_caldac(dev, CR_CHAN(insn->chanspec), data[0]); + if (insn->n) { + /* only bother writing the last sample to the channel */ + ni_write_caldac(dev, CR_CHAN(insn->chanspec), + data[insn->n - 1]); + } - return 1; + return insn->n; } static int ni_calib_insn_read(struct comedi_device *dev, -- cgit v1.2.3