Hi Sudeep, On Mon, 1 Aug 2022 at 13:28, Sudeep Holla <sudeep.ho...@arm.com> wrote: > > On Mon, Aug 01, 2022 at 01:13:23PM -0600, Simon Glass wrote: > > On Wed, 13 Apr 2022 at 10:46, Tom Rini <tr...@konsulko.com> wrote: > > > > > > How is it both discoverable and doesn't have a device tree node, in the > > > kernel? > > > > Also, if it is discoverable, we can still use U-Boot to discover it > > and then pass the info to Linux in the DT. > > > > Why ? Linux can discover the presence of the feature with a simple SMCCC > based query. We don't need any DT bindings for this particular feature. > Not sure if you are talking in general or in the context of $subject > feature in the kernel.
Oh well my understanding of Open Firmware was that the firmware did the probing and passed the info to the OS. > > > I am seeing several series which don't have 'proper' DT bindings in > > Linux. First I heard it was for legacy reasons, but now I am hearing > > something different. For U-Boot, we really do need to have DT bindings > > for devices. All this ad-hoc creation of stuff makes things hard to > > discover, adds to code size and makes things like of-platdata > > impossible. > > > > I may not have the complete picture here. If you are saying that every > feature in the u-boot needs DT for some reason, then that's U-boot's > limitation or restriction. But just the presence of node means nothing Yes it is something I am becoming more and more concerned about. > until the corresponding feature is queried and confirmed to be present > in the firmware. That is very important as we can't skip the query stage > just because of presence of some DT node for this. > > > Furthermore, if the bindings affect U-Boot, then the U-Boot project > > should have a say in what is being done there, not just be downstream > > of all such changes. > > > > I still think you talking about some issue in general and it doesn't > apply in this case. The new firmware interfaces are designed to be > discoverable which is the main advantage over any non discoverable > hardware and/or firmware interface. One main advantage I see is that we > don't need any DT bindings which makes the firmware upgrades must simpler > as the users can query the interface and know exactly what they need > instead of relying on DT node which may get stale if not updated with the > firmware update. I am not sure if whatever I am writing here is relevant > to what your concerns are as I think I haven't understood them fully. I'm not sure either. In particular I'm not sure why it would be easier to update whatever the FF-A software is than to update the DT, since presumably they are both in the firmware. I am talking about an issue in general and the same issue in particular with this series. Can I suggest resending this series with a change log for each patch. Also please try to avoid #ifdefs and make sure to include documentation in doc/ including how this relates to the UEFI firmware-update effort that ARM/Linaro is undertaking. Also, what happened to the tests / sandbox driver? Regards, Simon