From: Ian Abbott abbotti@mev.co.uk
commit 56c90457ebfe9422496aac6ef3d3f0f0ea8b2ec2 upstream.
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(-)
--- a/drivers/staging/comedi/drivers/mf6x4.c +++ b/drivers/staging/comedi/drivers/mf6x4.c @@ -121,8 +121,9 @@ static int mf6x4_ai_eoc(struct comedi_de 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; }