Hi Noralf, Peter Stuge wrote: > I'll prepare a test setup for the RGB-TFT on the weekend. So implementing a GUD and looking at the protocol from yet another angle gives more new insights - surprise. :) Here are some thoughts so far: * GUD_REQ_SET_VERSION does still rub me wrong; it seems potentially quite complex to maintain compatibility in two places; both for host and device. I don't want to insist on removing it, but at a minimum it's quite unusual. Part of the idea in USB is that host software updates are easy if not fully automated but device firmware updates less so, thus complexity is rather placed in the host. * It's unclear to me from reading the header files in this v6 patch set which GUD_REQ:s and which properties are actually mandatory in devices. I'm getting hints from your STM32 device and reading the driver code in detail, but what do you think is a good way to document what's required vs. optional? * GUD_REQ_SET_BUFFER my old nemesis. :) It's great that it's optional! But do you see any way to turn it into a bulk message, in order to remove the memory barrier effect of a control transfer before bulk? I think it would be possible to noticeably improve performance later, by changing the host driver to submit asynchronous bulk transfers for frame data rather than waiting for each transfer to finish; bulk transfers will then pack optimally on the wire - but with a control transfer in between there's no chance of achieving that. Having only one kind of transfer in the hot path would also simplify canceling still pending transfers (when using async later) if new data gets flushed before the previous frame is completely transfered. * A fair bit of the EDID isn't used or has dummy values. Have you already considered and dismissed some other ways of accomplishing the same? * Sorry if I've asked before - but what's the purpose of GUD_REQ_SET_STATE_CHECK and GUD_REQ_SET_STATE_COMMIT? Why/when does drm do pipe check vs. update? * How do you feel about passing the parameters for GUD_REQ_SET_CONTROLLER_ENABLE and GUD_REQ_SET_DISPLAY_ENABLE in wValue? It would save the transfer data stage. Kind regards //Peter
