Re: [PATCH v1] spi: add of_device_uevent_modalias support

[Marco Felsch <m.felsch@pengutronix.de>]

On 21-06-04 16:45, Mark Brown wrote:
> On Tue, May 25, 2021 at 11:10:03AM +0200, Marco Felsch wrote:
> > Add OF support as already done for ACPI to take driver
> > MODULE_DEVICE_TABLE(of, ..) into account.
> > 
> > For example with this change a spi nor device MODALIAS changes from:
> > 
> > MODALIAS=spi:spi-nor
> > 
> > to
> > 
> > MODALIAS=of:Nspi-flashT(null)Cjedec,spi-nor
> 
> Will this break existing userspace?

No, if I understood the mechanism correctly. 

The MODULE_DEVICE_TABLE(of, ..) and the MODULE_DEVICE_TABLE(spi, ..)
should equal except for the "vendor," prefix used by the
MODULE_DEVICE_TABLE(of, ..). If a driver don't support
MODULE_DEVICE_TABLE(of, ..) we fallback to the
MODULE_DEVICE_TABLE(spi, ..).

I would instead say that it fixes at least the spi-nor usage e.g.

spi-nor@0 {
	compatible = "vendor,product", "jedec,spi-nor";
}

is a common OF usage: the compatible list goes from the exact compatible
to the least common compatible. Here I should fix my commit message
which should include this line:
"MODALIAS=of:Nspi-flashT(null)Cwinbond,w25q16dwCjedec,spi-nor".

Anyway this scenario don't work for spi-nor driver since the spi-core
only take the MODULE_DEVICE_TABLE(spi, ..) into account. So the
compatible must not include the "vendor,product" compatible.

With my change in place we can specify the 'complete' compatible list.

Regards,
  Marco

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