В Wed, 9 Feb 2022 16:32:25 -0800 Julius Werner <jwerner@xxxxxxxxxxxx> пишет: > > I don't mind, but I also don't see where the revision-id property of > > LPDDR3 is used at all. I can't find any device-tree with LPDDR3 > > revision-id and don't see it being used in the code either. Maybe > > it's the LPDDR3 binding that needs to be changed? > > We are using the revision ID in userspace (read through > /proc/device-tree) for runtime memory identification. We don't have a > kernel driver bound to it. Our boot firmware is inserting this value > at runtime into the FDT (that's basically the reason we have this, our > firmware auto-detects memory during boot and we use the FDT to report > what it found to userspace), that's why you can't find it anywhere in > the static device trees in boot/dts/. Thank you for the clarification. Which device is that and why userspace needs to know so much about memory? > > I made each LPDDR2 revision-id property to correspond to a > > dedicated MR of LPDDR, which feels okay to me to since it matches > > h/w. > > I'm not super married to my solution, so if that makes things easier > we can standardize on the two-property version as well. I mostly > designed it my way because I thought we may one day also want to do > something like this for the 8-byte LPDDR5 serial-id, and then it would > get kinda cumbersome to have serial-id1 through serial-id8 all as > separate properties. But that's also a bridge we can cross when we get > there. > > My use case is in a position where we could still change this now > without requiring backwards-compatibility. Krzysztof, would you be > okay if I instead changed the "jedec,lpddr3" to the same thing > "jedec,lpddr2" does -- seeing as the original patch was from me, my > use case could handle the switch, there has never been any actual > kernel code using the property, and it seems very unlikely that anyone > else has silently started using the same thing in the time it's been > in the tree? Or do we also need to go the official deprecation route > for that? If you're going to use multiple cells for other properties, then indeed will be better to keep it consistent.
