* Andrew F. Davis <afd@xxxxxx> [191119 19:13]: > On 11/19/19 2:07 PM, Tony Lindgren wrote: > > * Andrew F. Davis <afd@xxxxxx> [191119 18:51]: > >> On 11/19/19 1:32 PM, Tony Lindgren wrote: > >>> It would allow us to completely change over to using > >>> arm_smccc_smc() and forget the custom calls. > >> > >> We would need more than just the r12 quirk to replace all our custom SMC > >> handlers, we would need quirks for omap_smc2 which puts process ID in r1 > >> and puts #0xff in r6, and omap_smc3 that uses smc #1. All of our legacy > >> SMC calls also trash r4-r11, that is very non SMCCC complaint as only > >> r4-r7 need be caller saved. I don't see arm_smccc_smc() working with > >> legacy ROM no matter how much we hack at it :( > > > > We would just have omap_smc2() call arm_smccc_smc() and in that > > case. And omap_smc2() would still deal with saving and restoring > > the registers. > > Then why call arm_smccc_smc()? omap_smc2() is already an assembly > function, all it needs to do after loading the registers and saving the > right ones is issue an "smc #0" instruction, why would we want to > instead call into some other function to re-save registers and issue the > exact same instruction? To use Linux generic API for smc calls where possible. > > Certainly the wrapper functions calling arm_smccc_smc() can deal > > with r12 too if the r12-quirk version and the plain version are > > never needed the same time on a booted SoC. > > > > Are they ever needed the same time on a booted SoC or not? ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Sorry but maybe check the font size on your screen. I'm trying to get your attention again for the second time above to answer a question I asked. > >> I can make OP-TEE also compatible with the r12 quirk, which is what I > >> used to do. That way we didn't need to do any detection. The issue was > >> that non-standard SMC calls should not go through the common SMCCC > >> handler (unless you are QCOM for some reason..). > > > > Sounds like for optee nothing must be done for r12 :) > Unless all our calls use the r12 hack, then we would need to fixup > OP-TEE to accept that also. No idea about that that part, but sounds like r12 use is up to the caller in the optee case. Regards, Tony
