On 11/03/21 9:18 pm, Wolfram Sang wrote: >> Bummer. What is really weird is that you see clock stretching under >> CPU load. Normally clock stretching is triggered by the device, not >> by the host. > One example: Some hosts need an interrupt per byte to know if they > should send ACK or NACK. If that interrupt is delayed, they stretch the > clock. > It feels like something like that is happening. Looking at the T2080 Reference manual there is an interesting timing diagram (Figure 14-2 if someone feels like looking it up). It shows SCL low between the ACK for the address and the data byte. I think if we're delayed in sending the next byte we could violate Ttimeout or Tlow:mext from the SMBUS spec.