Re: [PATCH 2/2] ARM: mvebu: Added dts defintion for Lenovo Iomega ix4-300d NAS

From: Jason Cooper
Date: Thu Jul 24 2014 - 10:56:46 EST

On Thu, Jul 24, 2014 at 04:29:18PM +0200, Andrew Lunn wrote:
> > The only outstanding point (Arnd?), is that I think it's ok to have the
> > i2c...a0 compatible string in the dts files, but Andrew seems to think
> > otherwise. Is that still true Andrew?
> Hi Jason
> I can live with i2c...a0 compatible string, but it has minor problems:
> 1) The binding Documentation says not to do it. So we are ignoring our
> own documentation.

This can be updated.

> 2) It seems likely that at some point the OEM will swap to B1 revision
> SoCs. The i2c device then does not require this quirk, but we have
> hard coded in the DT file that it is required. B1 revision would
> work, but not optimally.

The quirk can go both ways. eg, we can detect that we *aren't* on an A0
and need to remove the compatible string.

> So i would prefer not to explicitly enable the quirk, but determine at
> run time if the quirk is needed for the SoC revision it is running on.

I agree, but that is Linux-centric. We need to handle it coherently in
the binding docs for *BSD, bootloaders, etc.

I suggest we update the binding to allow using the compatible string,
and advise that to avoid end-user frustration, implementations should
detect the SoC revision at runtime and either add or remove the
compatible string.


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