Re: [PATCH v1 00/17] tee: Use bus callbacks instead of driver callbacks

Uwe Kleine-König
2025-12-15T09:32:21Z

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Hello Sumit,

On Mon, Dec 15, 2025 at 04:54:11PM +0900, Sumit Garg wrote:
> On Thu, Dec 11, 2025 at 06:14:54PM +0100, Uwe Kleine-König wrote:
> > Hello,
> >
> > the objective of this series is to make tee driver stop using callbacks
> > in struct device_driver. These were superseded by bus methods in 2006
> > (commit 594c8281f905 ("[PATCH] Add bus_type probe, remove, shutdown
> > methods.")) but nobody cared to convert all subsystems accordingly.
> >
> > Here the tee drivers are converted. The first commit is somewhat
> > unrelated, but simplifies the conversion (and the drivers). It
> > introduces driver registration helpers that care about setting the bus
> > and owner. (The latter is missing in all drivers, so by using these
> > helpers the drivers become more correct.)
> >
> > The patches #4 - #17 depend on the first two, so if they should be
> > applied to their respective subsystem trees these must contain the first
> > two patches first.
>
> Thanks Uwe for your efforts to clean up the boilerplate code for TEE bus
> drivers.

Thanks for your feedback. I will prepare a v2 and address your comments
(whitespace issues and wrong callback in the shutdown method).

> > Note that after patch #2 is applied, unconverted drivers provoke a
> > warning in driver_register(), so it would be good for the user
> > experience if the whole series goes in during a single merge window.
>
> +1
>
> I suggest the whole series goes via the Jens tree since there shouldn't
> be any chances for conflict here.
>
> > So
> > I guess an immutable branch containing the frist three patches that can
> > be merged into the other subsystem trees would be sensible.
> >
> > After all patches are applied, tee_bus_type can be made private to
> > drivers/tee as it's not used in other places any more.
> >
>
> Feel free to make the tee_bus_type private as the last patch in the series
> such that any followup driver follows this clean approach.

There is a bit more to do for that than I'm willing to invest. With my
patch series applied `tee_bus_type` is still used in
drivers/tee/optee/device.c and drivers/tee/tee_core.c. Maybe it's
sensible to merge these two files into a single one.

The things I wonder about additionally are:

- if CONFIG_OPTEE=n and CONFIG_TEE=y|m the tee bus is only used for
drivers but not devices.

- optee_register_device() calls device_create_file() on
&optee_device->dev after device_register(&optee_device->dev).
(Attention half-knowledge!) I think device_create_file() should not
be called on an already registered device (or you have to send a
uevent afterwards). This should probably use type attribute groups.
(Or the need_supplicant attribute should be dropped as it isn't very
useful. This would maybe be considered an ABI change however.)

- Why does optee_probe() in drivers/tee/optee/smc_abi.c unregister all
optee devices in its error path (optee_unregister_devices())?

Best regards
Uwe

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