On Thu, Jan 19, 2023 at 09:54:29AM -0700, Simon Glass wrote: > Hi Sudeep, > > On Thu, 19 Jan 2023 at 09:46, Sudeep Holla <sudeep.ho...@arm.com> wrote: > > > > Thanks for the details. But IIRC this discussion is not about the FF-A bus > > and device(partitions) discovery, but the support for FF-A itself. The > > discussion is about where to have a device node to represent the existence > > of > > FF-A support on a platform. If we are talking about individual partitions > > (devices) in the device tree, then that is pure stupidity as it goes out > > of since with the firmware the moment a partition is added or removed in > > the firmware. > > > > IIUC, the whole discussion was around whether to use FFA_VERSION as the > > discovery mechanism for existence of FF-A support on a platform or you > > have a device node to specify the same. > > No, with respect, that is not quite the situation here. >
Hmm, not sure what you mean by that. Based on your earlier response, I thought we are in agreement but you sound to differ here. Am I missing something ? > > > > Just to be clear, even if it is decided to add a device node, the > > FFA_VERSION must be used to detect the presence of FF-A support and > > return error otherwise. DT node presence is just to satisfy the design > > and must be treated as no auto-confirmation for the presence of FF-A > > support. We are just arguing the device node presence is just redundant, > > but as mentioned before it is up to U-Boot community to make a call on > > what is best. > > U-Boot driver model design already supports this. You can have a > device that binds (from DT) but will not probe because it is not > present / wrong version. Perhaps this was missed in the conversion to > Linux: > > https://u-boot.readthedocs.io/en/latest/develop/driver-model/design.html#driver-lifecycle > > So there is nothing clever needed here at all and anything you do just > adds confusion and bad precedent. > OK, I will give that a read. -- Regards, Sudeep