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From: Mika Westerberg <mika.westerberg@linux.intel.com>
Subject: Re: ACPI: Can I use I2cSerialBus with a PCI I2C controller?
Date: Mon, 2 Nov 2015 12:25:02 +0200
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To: Ben Gardner <gardner.ben@gmail.com>
Cc: Dustin Byford <dustin@cumulusnetworks.com>, linux-acpi@vger.kernel.org

On Fri, Oct 30, 2015 at 11:51:01AM -0500, Ben Gardner wrote:
> It looks like you are supposed to have the first compatible entry be
> the exact manufacturer,model.
> http://devicetree.org/Device_Tree_Usage#Understanding_the_compatible_Property
> 
> I am considering using a generic compatible entry ("linux,at24") to
> match the Linux at24 driver.
> In my case, I'm using a M24C02 from ST, so the compatible line would be:
> 
>   Package () {"compatible", Package () {"st,m24c02", "linux,at24"}},
>   Package () {"size", 256},
>   Package () {"pagesize", 16},
> 
> The "linux,at24" would require the other properties (size and
> pagesize) to be present.
> I've seen something similar done with a few other devices.

Using "linux,foo" is not a good idea and I'm pretty sure DT maintainers
will not take such patches. The compatible (and other properties as
well) should describe hardware not software.

> > Alternatively we may use the same _HID "INT3499" as Andy is doing in his
> > series with the below properties.
> 
> The only issue with reusing INT3499 is that it is configured to be a
> 24C08 in the at24 driver.
> Reusing the 24C08 HID for a 24C02 or other chip might be a bit confusing.

It could default to 24c08 but if it has properties the driver should use
those to determine size etc.