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    Subject[PATCH 05/32] staging: comedi: das08: improve test for programmable gain
    Date
    `das08_ai_rinsn()` handles Comedi `INSN_READ` instructions for the AI
    subdevice. This programs the gain for the analog input channel if the
    board has support for that, and acquires data from the channel. If
    programmable gain is supported, the gain code is read from the array
    pointed to by `devpriv->pg_gainlist` indexed by the range index. The
    function assumes that programmable gain is supported if the AI
    subdevice's range table supports more than one range. Replace that with
    a more direct test for `devpriv->pg_gainlist` being non-NULL, as it is
    only initialized to a non-NULL pointer for boards that support
    programmable gain.

    This will also allow range tables to be included for convenience for
    those boards that support multiple ranges by DIP switches. Those boards
    are currently initialized to use a single "unknown" range.

    Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
    ---
    drivers/staging/comedi/drivers/das08.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/drivers/staging/comedi/drivers/das08.c b/drivers/staging/comedi/drivers/das08.c
    index b1cd6ea..2521352 100644
    --- a/drivers/staging/comedi/drivers/das08.c
    +++ b/drivers/staging/comedi/drivers/das08.c
    @@ -225,7 +225,7 @@ static int das08_ai_rinsn(struct comedi_device *dev, struct comedi_subdevice *s,
    outb(devpriv->do_mux_bits, dev->iobase + DAS08_CONTROL);
    spin_unlock(&dev->spinlock);

    - if (s->range_table->length > 1) {
    + if (devpriv->pg_gainlist) {
    /* set gain/range */
    range = CR_RANGE(insn->chanspec);
    outb(devpriv->pg_gainlist[range],
    --
    2.1.4


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