* Andrew F. Davis <afd@xxxxxx> [191231 14:16]: > On 12/31/19 1:32 AM, Lokesh Vutla wrote: > > This doesn't guarantee that optee driver is probed successfully or firmware > > installed correctly. Isn't there a better way to detect? Doesn't tee core layer > > exposes anything? > > We don't actually need the kernel-side OP-TEE driver at all here, we are > making raw SMCCC calls which get handled by OP-TEE using platform > specific code then emulates the function previously handled by ROM[0] > and execution is returned. No driver involved for these types of calls. > > U-Boot will not add this node to the DT unless OP-TEE is installed > correctly, but you are right that is no perfect guarantee. OP-TEE's > kernel driver does do a handshake to verify it is working but this is > not exposed outside of that driver and happens *way* too late for our > uses here. Plus as above, we don't need the OP-TEE driver at all and we > should boot the same without it even enabled. > > So my opinion is that if DT says OP-TEE is installed, but it is not, > then that is a misconfiguration and we usually just have to trust DT for > most things. If DT is wrong here then the only thing that happens is > this call safely fails, a message is printed informing the user of the > problem, and kernel keeps booting (although probably not stable given we > need these calls for important system configuration). OK, please add comments to omap_optee_init_check(), it's not obvious to anybody not dealing with optee directly. Regards, Tony
