Re: [RFC] ACPI table HID/CID allocation

[Udit Kumar <udit.kumar@nxp.com>]

> -----Original Message-----
> From: Daniel Thompson [mailto:daniel.thompson@linaro.org]
> Sent: Thursday, November 23, 2017 1:42 AM
> To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Udit Kumar <udit.kumar@nxp.com>; Leif Lindholm
> <leif.lindholm@linaro.org>; edk2-devel@lists.01.org; Varun Sethi
> <V.Sethi@nxp.com>; Graeme Gregory <graeme.gregory@linaro.org>
> Subject: Re: [RFC] ACPI table HID/CID allocation
> 

> >
> > PRP0001 + compatible was invented to avoid the need to allocate a _HID
> > for each and every component in existence that can already be
> > identified by a DT compatible string (and little else except, e.g., a
> > I2C slave address) and is not deeply engrained in the SoC in terms of
> > clock tree, power states etc. So while internal/external may not be
> > the most accurate distinction, it is still a useful one IMHO.
> 
> Hmnnn.... it sounds like jedec,spi-nor meets this test.
> 
> There is only one property in the DT bindings that describes the device
> itself (fast read support) rather than its "bus address" (chip select,
> frequency). Further, that single property is obsolete, at least for
> Linux; the kernel driver now contains a quirks tables to look up by
> device ID whether fast read is supported and will use that on non-DT
> systems (and also to censor broken DT systems ;-) ).


You mean, this more on bus frame work, how to probe slave. 
Example rtc-ds3232.c , when is spi mode just need name 
but for i2c mode it needs of_match_table

Thanks 
Udit