Hi Martin,
Is there any specific reason why the new tpm2_tis_spi_xfer doesn't
support full duplex? It seems we did some work in parallel but you sent the patches earlier. Is that codes tested against an existing TPM v2? I have a working implementation what runs on SLB9670 including
full duplex.
What do you mean exactly?
I don't think the TPM2 protocol makes real use of full-duplex unless for the wait state between the host command and the actual xfer.
You are right, TIS 1.3 FIFO doesn’t use full duplex in physical level. What I
mean is that the driver you just wrote doesn't use the xfer function in that way that you can specify in and out parameters at same time. I did this in my implementation what gave me an easy chance to control the CS# of the TPM.
Do you need this CS# handling for more advanced features? Same question for the in/out xfers?
Can you tell me on what TPM did you test? For the SLB9670 the code doesn't work on my hardware.
I tested with a ST33TPHF20 SPI TPM.
I'm surprised it did not work with an SLB9670, I don't see anything in the spec explaining this CS# specificity.
The CS# may controls an internal state machine and the SLB9670 uses that signal.
For the code you wrote I'm considering to add a few lines to control the CS# in that way how my xfer is doing this for the SLB9670.
Yes please, share the patch and add me in cc so I could test it with mine.
Fine, will do so soon.
What's the status of this? I did not spot any patches, maybe you forgot to copy me? Otherwise do you still plan to share the changes? That would be great!
Thanks, Miquèl