From c34c739700f311d2ff1fb765e2407a69f91abda4 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Mon, 19 May 2014 11:29:04 +0100 Subject: 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 Reported-by: Fred Brooks Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/ni_daq_700.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers') diff --git a/drivers/staging/comedi/drivers/ni_daq_700.c b/drivers/staging/comedi/drivers/ni_daq_700.c index e4cdca34915..6417af0bdaa 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++) { -- cgit v1.2.3