Messages in this thread | | | Subject | Re: [PATCH v3 2/3] perf/smmuv3: Add a MODULE_SOFTDEP() to indicate dependency on SMMU | From | "Leizhen (ThunderTown)" <> | Date | Sat, 30 Jan 2021 09:34:55 +0800 |
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On 2021/1/30 1:03, Robin Murphy wrote: > On 2021-01-29 15:34, John Garry wrote: >> On 29/01/2021 15:12, Robin Murphy wrote: >>> On 2021-01-27 11:32, Zhen Lei wrote: >>>> The MODULE_SOFTDEP() gives user space a hint of the loading sequence. And >>>> when command "modprobe arm_smmuv3_pmu" is executed, the arm_smmu_v3.ko is >>>> automatically loaded in advance. >>> >>> Why do we need this? If probe order doesn't matter when both drivers are built-in, why should module load order? >>> >>> TBH I'm not sure why we even have a Kconfig dependency on ARM_SMMU_V3, given that the drivers operate completely independently :/ >> >> Can that Kconfig dependency just be removed? I think that it was added under the idea that there is no point in having the SMMUv3 PMU driver without the SMMUv3 driver. > > A PMCG *might* be usable for simply counting transactions to measure device activity regardless of its associated SMMU being enabled.
If that's the case, the SOFTDEP really shouldn't be added. I wasn't trying to make sure they were loaded in order, just to make sure that the SMMU was not forgotten to load.
> Either way, it's not really Kconfig's job to decide what makes sense (beyond the top-level "can this driver *ever* be used on this platform" visibility choices). Imagine if we gave every PCI/USB/etc. device driver an explicit ?dependency on at least one host controller driver being enabled... > > Robin. > > . >
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