If you're referring to the way the spi_message and spi_transfer
structs sit in the same cache lines as the data buffers, that's
something that should get fixed.

Yes, that's what my patch did. The "strange" part is using a single
malloc instead of three (re-reading your message, the full-duplex
isn't involved here, so I'm not sure tx and rx data can safely be
merged in a cache line).

It seems that e8f462d202026d8e99f553ed5a09422321226ac9 wasn't a
complete fix ... this explains why the touchscreen behaves but
not the ADC inputs (as you noted).

Yes, basically I did the same split of data from control.

Note that this issue is unrelated to full duplex DMA support.

Yes, that's right. But full duplex is not involved here, it's
just 2 or 3 rounds of "one byte tx then two bytes rx".

/alessandro