I personally still have to see one of the M.2 NVMe which requires the subclock.The only significant thing I'm aware of that the Raspberry Pi M.2 HAT does differently to other third-party boards is that it includes an on-board 32.768 kHz oscillator that provides Suspend Clock (SUSCLK). Apparently some M.2 drives didn't work properly without this, although the majority don't use it, hence why many third-party boards don't provide it. Other than that, there's really not a lot an M.2 adapter board can do to affect compatibility - after all, M.2 is essentially just straight-through PCI Express with a few additional control signals. Compatibility issues are largely between the Pi and the SSD.I thought the raspberry pi HAT overcame whatever issues the earlier released third party boards had, because the raspberry pi documentation says :-
The M.2 HAT+ adapter board converts between the PCIe connector on Raspberry Pi 5 and a single M.2 M key edge connector. You can connect any device that uses the 2230 or 2242 form factors
I also interpret that statement in context of its qualifier - that any device that conforms to the appropriate form factor can be physically connected. Not that it is compatible with any device.
What I've experienced myself is firmware related topics which I don't know who to blame for. A device working on CM4 was non-working on Pi5 but could be convinced to work on Pi5 after an NVMe drive firmware update --> who to blame here?
As long as nobody is willing to explain the real differences in the interface (CM4 compared to Pi5) it remains gambling: either working or not! Maybe you can make a second call in case one is able to flash/check with another firmware but that's another high-risk gamble on it's own.
You can't even make recommendations (or not) on product level as there might be deviations (different flash chip -> different FW --> not working on Pi5 because of that).
Is there a workaround possibility from using the triggers in https://github.com/raspberrypi/linux/bl ... verlay.dts and https://github.com/raspberrypi/linux/bl ... verlay.dts ? Maybe, but I personally could not work out one so far during my testings.
Quoting from https://datasheets.raspberrypi.com/m2-h ... -brief.pdf
• Supports devices that use the M.2 M key edge connector
• Supports devices with the 2230 or 2242 form factor
That's not making any limitations though (although I need to say that I'm not a native English speaker).
Statistics: Posted by aBUGSworstnightmare — Wed Jun 26, 2024 1:59 pm