On 8/03/21 5:59 pm, Guenter Roeck wrote: > On 3/7/21 8:37 PM, Chris Packham wrote: > [ ... ] >>> That's from -ENXIO which is used in only one place in i2c-mpc.c. I'll >>> enable some debug and see what we get. >> For the errant readings there was nothing abnormal reported by the driver. >> >> For the "No such device or address" I saw "mpc-i2c ffe119000.i2c: No >> RXAK" which matches up with the -ENXIO return. >> > Id suggest to check the time until not busy and stop in mpc_xfer(). > Those hot loops are unusual, and may well mess up the code especially > if preempt is enabled. Also, are you using interrupts or polling in > your system ? I'm using interrupts but I see the same issue if I comment out the interrupts in the dtsi file (i.e. force it to use polling). > The interrupt handler looks a bit odd, with "Read again > to allow register to stabilise". Yeah that stuck out to me too. The code in question predates git, I went spelunking in history.git and the "Read again" seems to be in the initial version[0]. I did try to alter the interrupt handler so that it only does one read but that didn't seem to change anything. > Do you have fsl,timeout set in the devicetree properties and, if so, > have you played with it ? Haven't got it set but I'll have a go at tweaking it. > Other than that, the only other real idea I have would be to monitor > the i2c bus. I am in the fortunate position of being able to go into the office and even happen to have the expensive scope at the moment. Now I just need to find a tame HW engineer so I don't burn myself trying to attach the probes. -- [0] - https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=11b3235dc04a306f6a9ba14c1ab621b2d54f2c56
