Hello.

Laurent Pinchart wrote:

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here is the sram entry in our dts:

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Except that your implementation of it is not good.

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You're relying on the old obsolete flash binding with the "probe-type"
field.  The solution should be adapted to the new approach which uses
values in the "compatible" field to indicate various sorts of flash
device.

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What "compatible" values should I use for ROM and RAM mappings ?

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That I'm not so sure of.  We'll need to find some consensus.

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There may be existing IEEE1275 bindings for roms, which we should
investigate.

Do you (or someone else here) have access to the IEEE1275 specification ? Is 

    Yeah, and I can point you to it -- see the documantation section on 
http://www.openbios.org/...

there any ROM binding in there ?

    No. We initially called the flash devices that physmap_of driver 
controlled "rom" (I mean the "device_type" property) -- now this is obsoleted.

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Arguably RAM should be represented by a memory node, but 
that's going to get messy for this sort of application.

    Note that the OF "memory" type nodes do *not* represent RAM devices.

We're talking about a very specific type of RAM, used for permanent storage 
with a battery backup. The RAM is really meant to be used as an MTD device 
and as such I think it makes sense to describe it as an mtd-compatible device 
on the local bus.

What about the following definition for the RAM node ?

        nvram@2,0000 {

    Note that there's a OF "device_type" of "nvram", so your (generic) device 
name seems to add some mess. (IIRC, that OF device type didn't actually 
represent a "real" device, and only served to provide access to NVRAM for OF).

                compatible = "mtd,ram";

    The part before comma should be a company name or a stock ticker. What did 
you mean here?

                reg = <2 0x0000 0x00100000>;
                bank-width = <2>;
        };

Or should the node have a device-type property of either 'ram' or 'rom' with 
the compatible property just referencing MTD ?

    The "device_type" properties are not required and their further creation 
has been discouraged on liunxppc-dev.

Best regards,

WBR, Sergei