On 1/2/20 12:14 PM, Tony Lindgren wrote: > * 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. > Okay, will add this comment and the one suggested by Lokesh for v4. Andrew > Regards, > > Tony >
