Re: [PATCH] soc: imx8m: Probe the SoC driver late

[Marek Vasut]

On 9/25/24 6:31 PM, Arnd Bergmann wrote:
> On Wed, Sep 25, 2024, at 16:09, Marek Vasut wrote:
> > On 9/25/24 6:04 PM, Arnd Bergmann wrote:
> > > On Wed, Sep 25, 2024, at 16:00, Marek Vasut wrote:
> > > > With driver_async_probe=* on kernel command line, the following trace is
> > > > produced because on i.MX8M Plus hardware because the soc-imx8m.c driver
> > > > calls of_clk_get_by_name() which returns -EPROBE_DEFER because the clock
> > > > driver is not yet probed. This was not detected during regular testing
> > > > without driver_async_probe.
> > > >
> > > > Attempt to fix it by probing the SoC driver late, but I don't think that
> > > > is the correct approach here.
> > >
> > > I think the correct fix would be to propagate the -EPROBE_DEFER
> > > and return that from imx8_soc_init(), so it gets retried again
> > > after the clock driver.
> > I already tried that, but if I return -EPROBE_DEFER from
> > device_initcall, it doesn't get retriggered . I suspect EPROBE_DEFER
> > works only for proper drivers ?
>
> Right, of course. And unfortunately it can't just register to
> the fsl,imx8mm-anatop/fsl,imx8mm-ocotp/... nodes because they
> all have a driver already.
>
> On the other hand, making it a late_initcall() defeats the
> purpose of the driver because then it can't be used by other
> drivers with soc_device_match(), resulting in incorrect
> behavior when another driver relies on this to enable
> a chip revision specific workaround.
I know, I am unsure how to proceed with this. Convert this to 
platform_driver or some such and probe it early maybe ?