On Tue, Jul 18, 2023 at 12:10:16PM -0700, Nikunj Kela wrote: > > On 7/18/2023 12:07 PM, Bjorn Andersson wrote: > > On Tue, Jul 18, 2023 at 11:53:24AM -0700, Nikunj Kela wrote: > > > On 7/18/2023 11:29 AM, Bjorn Andersson wrote: > > > > On Tue, Jul 18, 2023 at 09:08:33AM -0700, Nikunj Kela wrote: > > > > > diff --git a/drivers/firmware/arm_scmi/qcom_hvc.c b/drivers/firmware/arm_scmi/qcom_hvc.c > > [..] [..] > > > > > +#ifdef CONFIG_ARM64 > > > > > + cap_id = readq((void *)(scmi_info->shmem) + size + > > > > > + sizeof(unsigned long)); > > > > > +#else > > > > > + cap_id = readl((void *)(scmi_info->shmem) + size + > > > > > + sizeof(unsigned long)); > > > > > +#endif > > > > Please don't make the in-memory representation depend on architecture > > > > specific data types. Quite likely you didn't compile test one of these > > > > variants? > > > > > > > > Just define the in-memory representation as u32 + u64. > > > I tested this for ARM64, I didn't test it for 32bit since Hypervisor doesn't > > > support it currently. In future, it may add 32 bit support too. > > I'd not be surprised if the capability id is 64 bit on a 32-bit machine > > as well, it's not really a property of the architecture. > > on 32bit machine, you will have to use SMC32 convention. lt will mean that > the parameters can only be 32 bit long. If you keep cap-id 64 bit in 32bit > machines, then it has to be passed in two parameters. Are you suggesting, I > make this driver dependent on ARM64 and only care about 64 bit for now? > I'm suggesting that the calling convention is one thing and the in-memory format for passing the information to the driver is a different thing. Keep the arguments passed in memory architecture-independent (i.e. make it u64). If you're saying that the calling convention would be different on a 32-bit system, then you are also saying that your driver _is_ 64-bit specific. Please confirm what the size of your capability id would be in such a system and make sure the Kconfig and/or the code, reflects reality. Thanks, Bjorn
