On 10/03/21 6:06 pm, Guenter Roeck wrote: > On 3/9/21 6:19 PM, Chris Packham wrote: >> On 9/03/21 9:27 am, Chris Packham wrote: >>> On 8/03/21 5:59 pm, Guenter Roeck wrote: >>>> 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. >> One thing I see on the scope is that when there is a CPU load there >> appears to be some clock stretching going on (SCL is held low some >> times). I don't see it without the CPU load. It's hard to correlate a >> clock stretching event with a bad read or error but it is one area where >> the SMBUS spec has a maximum that might cause the device to give up waiting. >> > Do you have CONFIG_PREEMPT enabled in your kernel ? But even without > that it is possible that the hot loops at the beginning and end of > each operation mess up the driver and cause it to sleep longer > than intended. Did you try usleep_range() ? I've been running with and without CONFIG_PREEMPT. The failures happen with both. I did try usleep_range() and still saw failures. > On a side note, can you send me a register dump for the lm81 ? > It would be useful for my module test code. Here you go this is from a largely unconfigured LM81 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef 00: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG 10: 47 81 24 03 94 00 00 00 00 ff ff ff ff ff ff ff G?$??........... 20: bf cb c1 00 c0 47 ec 24 ff ff 65 ff 00 ff 00 ff ???.?G?$..e..... 30: 00 ff 00 ff 00 ff 00 71 a9 7f 7f ff ff 58 01 04 .......q???..X?? 40: 01 08 00 00 00 00 00 50 2f 80 80 01 44 00 00 00 ??.....P/???D... 50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 90: 00 81 24 03 94 00 00 00 00 ff ff ff ff ff ff ff .?$??........... a0: bf cb c1 00 c0 47 ec 24 ff ff 65 ff 00 ff 00 ff ???.?G?$..e..... b0: 00 ff 00 ff 00 ff 00 71 a9 7f 7f ff ff 58 01 04 .......q???..X?? c0: 01 00 00 00 00 00 00 50 2f 80 80 01 44 00 00 00 ?......P/???D... d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ This is from a LM81 that's been configured by our application SW with limits appropriate for the platform. 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef 00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 10: ff 81 24 03 94 00 00 00 00 ff ff ff ff ff ff ff ..$............. 20: bf cc c1 00 c0 47 ec 1c ff ff 65 dc b4 ff c0 d3 .....G....e..... 30: ad ff 00 d3 ad 4e 40 71 a9 4b 46 ff ff 58 01 04 .....N@xxxx..X.. 40: 01 08 00 00 00 00 00 f0 2f 80 80 81 44 80 80 80 ......../...D... 50: 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 ................ 60: 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 ................ 70: 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 ................ 80: 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 ................ 90: 80 81 24 03 94 00 00 00 00 ff ff ff ff ff ff ff ..$............. a0: bf cc c1 00 c0 47 ec 1c ff ff 65 dc b4 ff c0 d3 .....G....e..... b0: ad ff 00 d3 ad 4e 40 71 a9 4b 46 ff ff 58 01 04 .....N@xxxx..X.. c0: 01 00 00 00 00 00 00 f0 2f 80 80 81 44 80 80 80 ......../...D... d0: 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 ................ e0: 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 ................ f0: 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 ................
