Have you ever successfully brought up a DSI panel on any platform?
DSI is a pig of an interface as it has a large number of options at both the DSI and D-PHY levels. You also then get fairly generic TCONs (Timing Controller) that interface with a panel, and they each have their own set of requirements. If you haven't got full details from the display manufacturer for exactly the timings and initialisation sequences required, then it is pretty much guesswork as you have no way of getting debug from the display, it just doesn't work.
We've been through it with one panel where ended up hooking an scope onto the DSI bus between an HDMI to DSI adapter board for the panel, and looking at what the adapter sent during initialisation. It didn't match what the manufacturer had told us was the correct initialisation sequence, but using it as the basis for the kernel driver made the panel work.
If you can get an HDMI adapter board for your particular display, then analysing what it does is often an easier route forward. Typically the init sequences are sent in LP mode, which means you only need to monitor data lane 0. A number of scopes also have the option to do D-PHY LP mode decoding for you (we added the relevant licence to our Rohde & Schwarz RTE1204), although it can be done manually if you read the D-PHY spec.
DSI is a pig of an interface as it has a large number of options at both the DSI and D-PHY levels. You also then get fairly generic TCONs (Timing Controller) that interface with a panel, and they each have their own set of requirements. If you haven't got full details from the display manufacturer for exactly the timings and initialisation sequences required, then it is pretty much guesswork as you have no way of getting debug from the display, it just doesn't work.
We've been through it with one panel where ended up hooking an scope onto the DSI bus between an HDMI to DSI adapter board for the panel, and looking at what the adapter sent during initialisation. It didn't match what the manufacturer had told us was the correct initialisation sequence, but using it as the basis for the kernel driver made the panel work.
If you can get an HDMI adapter board for your particular display, then analysing what it does is often an easier route forward. Typically the init sequences are sent in LP mode, which means you only need to monitor data lane 0. A number of scopes also have the option to do D-PHY LP mode decoding for you (we added the relevant licence to our Rohde & Schwarz RTE1204), although it can be done manually if you read the D-PHY spec.
Statistics: Posted by 6by9 — Tue Dec 19, 2023 9:55 pm