Messages in this thread | | | Date | Mon, 09 Feb 2015 13:27:58 -0800 | From | Laura Abbott <> | Subject | Re: [PATCH/RFC 0/4] Probe deferral for IOMMU DT integration |
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On 2/7/2015 2:41 PM, arnd@arndb.de wrote: > Laura Abbott <lauraa@codeaurora.org> hat am 6. Februar 2015 um 01:31 > geschrieben: >> >> The requirement for this is based on a previous patch to add clock >> support to the ARM SMMU driver[2]. Once we have clock support, it's >> possible that the driver itself may need to be defered which breaks >> a bunch of assumptions about how SMMU probing is supposed to work. > > Hi Laura, > > I was hoping that we would not need this, and instead treat the iommu in > the same way as timers and SMP initialization, both > of which need to be run early at boot time but may rely on clock controllers > to be initialized first. > > Is there a specific requirement that makes this impossible here, or is your > intention to solve the problem more nicely by allowing deferred probing > over forcing the input clocks of the iommu to be early? > > Arnd >
The current clock driver for qcom targets doesn't support the early initialization needed for timers and SMP because neither of those depend on the clocksources. I discussed this with Stephen some and adding the early support would not mesh well with the device/driver design of the current clock driver so that's not really an option right now.
I do think the deferred probing design is cleaner. Even cleaner would be a proper bus type but that's a different can of worms.
Thanks, Laura
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