This is a note to let you know that I've just added the patch titled

staging: comedi: mf6x4: Fix AI end-of-conversion detection

to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-testing branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will be merged to the staging-next branch sometime soon, after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.

From 56c90457ebfe9422496aac6ef3d3f0f0ea8b2ec2 Mon Sep 17 00:00:00 2001

From: Ian Abbott abbotti@mev.co.uk Date: Mon, 7 Dec 2020 14:58:06 +0000 Subject: staging: comedi: mf6x4: Fix AI end-of-conversion detection

I have had reports from two different people that attempts to read the analog input channels of the MF624 board fail with an `ETIMEDOUT` error.

After triggering the conversion, the code calls `comedi_timeout()` with `mf6x4_ai_eoc()` as the callback function to check if the conversion is complete. The callback returns 0 if complete or `-EBUSY` if not yet complete. `comedi_timeout()` returns `-ETIMEDOUT` if it has not completed within a timeout period which is propagated as an error to the user application.

The existing code considers the conversion to be complete when the EOLC bit is high. However, according to the user manuals for the MF624 and MF634 boards, this test is incorrect because EOLC is an active low signal that goes high when the conversion is triggered, and goes low when the conversion is complete. Fix the problem by inverting the test of the EOLC bit state.

Fixes: 04b565021a83 ("comedi: Humusoft MF634 and MF624 DAQ cards driver") Cc: stable@vger.kernel.org # v4.4+ Cc: Rostislav Lisovy lisovy@gmail.com Signed-off-by: Ian Abbott abbotti@mev.co.uk Link: https://lore.kernel.org/r/20201207145806.4046-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/staging/comedi/drivers/mf6x4.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/comedi/drivers/mf6x4.c b/drivers/staging/comedi/drivers/mf6x4.c index ea430237efa7..9da8dd748078 100644 --- a/drivers/staging/comedi/drivers/mf6x4.c +++ b/drivers/staging/comedi/drivers/mf6x4.c @@ -112,8 +112,9 @@ static int mf6x4_ai_eoc(struct comedi_device *dev, struct mf6x4_private *devpriv = dev->private; unsigned int status;

+ /* EOLC goes low at end of conversion. */ status = ioread32(devpriv->gpioc_reg); - if (status & MF6X4_GPIOC_EOLC) + if ((status & MF6X4_GPIOC_EOLC) == 0) return 0; return -EBUSY; }