Messages in this thread | | | From | Arnd Bergmann <> | Date | Mon, 13 Mar 2017 13:41:25 +0100 | Subject | Re: [PATCH 2/2] [RFC] base: soc: Allow early registration of a single SoC device |
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On Thu, Mar 9, 2017 at 7:18 PM, Geert Uytterhoeven <geert+renesas@glider.be> wrote: > commit 1da1b3628df34a2a ("base: soc: Early register bus when needed") > added support for early registration of SoC devices from a > core_initcall(). However, some drivers need to check the SoC revision > from an early_initcall(), which is even earlier. > > While registering the SoC bus and device, and using soc_device_match(), > from an early_initcall() do work, the "soc" directory and the "soc0" > file end up wrongly in the sysfs root, as the "bus" resp. "devices" > directories haven't been created yet. > > To fix this, allow to register a single SoC device early on. > As long as the SoC bus isn't registered, soc_device_match() just > matches against this early device. > When the SoC bus is registered later, the early device is registered for > real. > > Note that soc_device_register() returns NULL (no error, but also not a > valid pointer) when registering an early device. Hence platform devices > cannot be instantiated as children of the "soc0" node representing an > early SoC device. This should not be an issue, as that practice has > been deprecated for new platforms. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > --- > Is there a better way to fix this? > While I believe all current users register a single SoC device, we may > want to register multiple SoC devices in the future? > > soc_device_match() itself is completely independent from sysfs, but the > sysfs operations are tied intimately to the driver core. > > The "bus" and "devices" directories are created from do_basic_setup() -> > driver_init() -> devices_init() / buses_init(), which runs in between > do_pre_smp_initcalls() (early_initcall()) and do_initcalls().
I'd prefer to not have to do the early registration at all and have fewer special cases. Can you list a specific example that requires this?
If we want to do early registration, then your implementation seems fine to me.
Arnd
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