diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2014-05-19 11:29:04 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-06-11 11:54:12 -0700 |
| commit | 0cd6fa616912431665fb9d30bb96a1247b9c6304 (patch) | |
| tree | bcc919e1ff4c9e73b412b5d79c173240e1037e30 | |
| parent | 3bf5072cf916c0da7f789063c5bcc455b89ee929 (diff) | |
staging: comedi: ni_daq_700: add mux settling delay
commit ffed54dced86723f352323f15789d9ad6bee25e1 upstream.
I got a patch from the original author, Fred Brooks, to add a small
settling delay after setting the AI channel multiplexor. The lack of
delay resulted in unstable or scrambled data on faster processors.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reported-by: Fred Brooks <nsaspook@nsaspook.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/comedi/drivers/ni_daq_700.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/staging/comedi/drivers/ni_daq_700.c b/drivers/staging/comedi/drivers/ni_daq_700.c index e4cdca349157..6417af0bdaab 100644 --- a/drivers/staging/comedi/drivers/ni_daq_700.c +++ b/drivers/staging/comedi/drivers/ni_daq_700.c @@ -122,6 +122,8 @@ static int daq700_ai_rinsn(struct comedi_device *dev, /* write channel to multiplexer */ /* set mask scan bit high to disable scanning */ outb(chan | 0x80, dev->iobase + CMD_R1); + /* mux needs 2us to really settle [Fred Brooks]. */ + udelay(2); /* convert n samples */ for (n = 0; n < insn->n; n++) { |