On Wed, Apr 07, 2021 at 05:12:06PM -0700, Stephen Boyd wrote: > Quoting Stephan Gerhold (2021-04-05 05:50:26) > > On Fri, Apr 02, 2021 at 10:21:58AM -0700, Stephen Boyd wrote: > > > > > > Ah right, the whole secure world running in 32-bit mode thing. Is > > > msm8916 the only SoC that's using that? Or are there more? If only > > > msm8916 is affected then we could use a combination of CONFIG_ARM64 and > > > the compatible string to differentiate and then if more SoCs use 32-bit > > > secure world then we could have a new compatible string like qcom,scm-32 > > > that tells us this fact. Maybe this was all discussed before and I > > > missed it. Either way, I'm trying to get rid of this boot call so that > > > we don't have to bounce to the firmware an extra time to figure out > > > something we can figure out from the kernel arch and scm compatible > > > string. > > > > At least MSM8994 also uses SMC32 from what I heard. Overall it's > > probably quite hard to get that right now since all boards were tested > > with the dynamic detection so far. I suppose you could do the opposite, > > add an optional qcom,scm-64 to skip the detection step and force SMC64. > > Isn't SMC64 going to be the overall majority going forward? Legacy > convention is for sure limited to CONFIG_ARM so I'll send another > follow-up patch to add a warning if we find legacy on CONFIG_ARM64. > SMC32 is hopefully no longer being produced given that it was introduced > at the time that the bootloader team wasn't supporting PSCI and didn't > want to support it. So we're making all new boards/SoCs/firmwares do > this calling convention probing to figure out something they already > know? > > Maybe we should probe the calling convention on msm8994/msm8916 and > otherwise assume SMC64 on CONFIG_ARM64 kernels. I'd expect the exception > list to be smaller that way. > Personally, I think it would be best to introduce a new, SMC64 only compatible (e.g. "qcom,scm-64" like I mentioned). Then you can skip the detection check for the boards that opt-in by adding the compatible. You can then use it on all newer boards/SoCs/firmwares where you know exactly that there is SMC64. I would just like to avoid breaking any existing boards where we don't know exactly if they have SMC32 or SMC64. > > > > Also note that this could even be firmware-specific, not necessarily > > SoC-specific. There are some ancient MSM8916 firmwares that have legacy > > instead of SMC32. I could also imagine that there is also some SoC where > > there are different firmware versions with SMC32 or SMC64. > > Sure but in theory the firmware would update the DT to indicate what > sort of firmware is there. > In a perfect world the firmware would do that, but there is certainly no such mechanism on any of the old SoCs :/ > > > > Plus, IMO the overhead for this detection is negligible. At least it > > ensures that we always use the right calling convention. The PSCI code > > probably does much more firmware calls to figure out all supported > > features. > > > > Heh, it tried to ensure we use the right calling convention but broke > things in the process, because the way of detecting the convention isn't > always there. I wouldn't be surprised if this comes up again for other > boards that use TF-A. Ah okay, this sounds like a better reason than just trying to avoid the "overhead" of the detection step. :) I still think it should work if you just start marking all newer boards/SoCs/... as "qcom,scm-64" or something like that, right? Thanks, Stephan
