Messages in this thread | | | Date | Tue, 08 Sep 2015 21:01:20 +0800 | From | Hanjun Guo <> | Subject | Re: [PATCH 1/5] acpi: Add basic device probing infrastructure |
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On 09/08/2015 05:57 PM, Marc Zyngier wrote: > On 07/09/15 22:29, Rafael J. Wysocki wrote: >> On Friday, September 04, 2015 06:06:48 PM Marc Zyngier wrote: >>> IRQ controllers and timers are the two types of device the kernel >>> requires before being able to use the device driver model. >>> >>> ACPI so far lacks a proper probing infrastructure similar to the one >>> we have with DT, where we're able to declare IRQ chips and >>> clocksources inside the driver code, and let the core code pick it up >>> and call us back on a match. This leads to all kind of really ugly >>> hacks all over the arm64 code and even in the ACPI layer. >>> >>> In order to allow some basic probing based on the ACPI tables, >>> introduce "struct acpi_probe_entry" which contains just enough >>> data and callbacks to match a table, an optional subtable, and >>> call a probe function. A driver can, at build time, register itself >>> and expect being called if the right entry exists in the ACPI >>> table. >>> >>> A acpi_probe_device_init() is provided, taking an ACPI table >>> identifier, and iterating over the registered entries. >> >> What about things that are provided by the ACPI namespace (eg. via _MAT) rather >> than in static tables? > > By the time we get to process non-static tables, the whole probing > infrastructure (including the ACPI interpreter) should be up and > running. I'm not seeing this stuff as a replacement for more dynamic > things - quite the opposite. It is only to be used for early bring-up.
Yes, this framework is for static tables and used at boot time, sometimes quite early, which is before acpi_early_init().
But for _MAT (which is used for dynamic device configuration), it's really a good question, I think _MAT is mainly for CPU hotplug, and it's not related to this framework (for GIC init and clock source). To hot add/remove a whole ARM SoC with _MAT, I think we need more time to make the spec ready first, that's long term work, and agian it's nothing to do with this infrastructure if I understand correctly :)
Thanks Hanjun
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