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| author |   Ian Abbott <abbotti@mev.co.uk> | 2014-05-19 11:29:04 +0100 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-05-24 01:31:35 +0900 |
| commit | ffed54dced86723f352323f15789d9ad6bee25e1 (patch) | |
| tree | 39d666af5d6c06ccf850cdf8b3de50a6e3c1f5b2 /drivers | |
| parent | speakup: fix incorrect perms on speakup_acntsa.c (diff) | |
| download | linux-dev-ffed54dced86723f352323f15789d9ad6bee25e1.tar.xz linux-dev-ffed54dced86723f352323f15789d9ad6bee25e1.zip | |
staging: comedi: ni_daq_700: add mux settling delay
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>
Cc: <stable@vger.kernel.org> # 3.7.x - 3.15.x
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -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 171a71d20c88..728bf7f14f7b 100644 --- a/drivers/staging/comedi/drivers/ni_daq_700.c +++ b/drivers/staging/comedi/drivers/ni_daq_700.c @@ -139,6 +139,8 @@ 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++) { |