Clock-stretching has corrupted SMBus data. about rpupi HOT 2 CLOSED

Interleaving between two buffers (A and B) within the ISR used by SMBus seems to have done the trick.

089455a#diff-5bd95c1d69122d988a6f85757b66c817

The buffer used by the ISR is swapped after passing it to the user (e.g., with receive callback function). The user receive function runs within the ISR context, but now it can be concise (e.g., save the pointer and byte count). Then all the work can be done outside of ISR context since the buffer is no longer in the risk of being changed, at least until a subsequent receive event when it will be swapped back into service.

089455a#diff-e5edda6dc80c252451acc1b2be91d078

The quick receive event seems to be tolerated by the R-Pi's clock, but more testing is needed. The handle_smbus function is run in the main loop if there are SMBus bytes available.

I have read about a lot of I2C problems over the years; I guess it is difficult to do the hardware.

from rpupi.

A fair amount of SMBus commands have been sent without any errors, so I am going to call this fixed.

from rpupi.