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 12:03:25 -0700 |
| commit | f3c0ca9b1ac4282922f6ef75fef5f7cb9f913cfc (patch) | |
| tree | 8a0dd40034fb82b1b9a3e944db540dadf9c467a7 | |
| parent | e7eb1ab9a3bb72caa580688f26e582ce29343f6b (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 d067ef70e194..5e80d428e544 100644 --- a/drivers/staging/comedi/drivers/ni_daq_700.c +++ b/drivers/staging/comedi/drivers/ni_daq_700.c @@ -127,6 +127,8 @@ 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++) { |