From: Sergei Shtylyov <sshtylyov@ru•mvista.com>
To: Laurent Pinchart <laurentp@cse-semaphore•com>
Cc: ben@simtec•co.uk, linuxppc-dev@ozlabs•org,
linux-mtd@lists•infradead.org,
David Gibson <david@gibson•dropbear.id.au>
Subject: Re: OF compatible MTD platform RAM driver ?
Date: Tue, 25 Mar 2008 18:29:31 +0300 [thread overview]
Message-ID: <47E91A5B.1060406@ru.mvista.com> (raw)
In-Reply-To: <200803251536.17795.laurentp@cse-semaphore.com>
Hello.
Laurent Pinchart wrote:
>>>>>here is the sram entry in our dts:
>>>>Except that your implementation of it is not good.
>>>>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.
>>>What "compatible" values should I use for ROM and RAM mappings ?
>>That I'm not so sure of. We'll need to find some consensus.
>>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.
>>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
next prev parent reply other threads:[~2008-03-25 15:28 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-10 15:06 OF compatible MTD platform RAM driver ? Laurent Pinchart
2008-03-10 17:00 ` Rune Torgersen
2008-03-11 0:45 ` David Gibson
2008-03-11 10:39 ` Laurent Pinchart
2008-03-11 22:40 ` David Gibson
2008-03-25 14:36 ` Laurent Pinchart
2008-03-25 15:29 ` Sergei Shtylyov [this message]
2008-03-25 15:51 ` Laurent Pinchart
2008-03-25 16:23 ` Sergei Shtylyov
2008-03-25 16:44 ` Laurent Pinchart
2008-03-25 17:02 ` Sergei Shtylyov
2008-03-25 17:23 ` Laurent Pinchart
2008-03-25 17:37 ` Sergei Shtylyov
2008-03-25 17:56 ` Rune Torgersen
2008-03-25 18:14 ` Laurent Pinchart
2008-03-26 12:53 ` Sergei Shtylyov
2008-03-27 9:13 ` Laurent Pinchart
2008-03-27 10:03 ` David Gibson
2008-03-27 12:23 ` Sergei Shtylyov
2008-03-28 0:07 ` David Gibson
2008-03-28 12:31 ` Sergei Shtylyov
2008-03-27 14:31 ` Laurent Pinchart
2008-03-28 0:09 ` David Gibson
2008-03-30 18:15 ` Segher Boessenkool
2008-03-30 21:16 ` Paul Mackerras
2008-03-30 22:39 ` Segher Boessenkool
2008-03-31 0:42 ` Paul Mackerras
2008-03-31 0:59 ` Segher Boessenkool
2008-03-31 1:24 ` Segher Boessenkool
2008-03-31 8:21 ` Laurent Pinchart
2008-03-31 12:21 ` Segher Boessenkool
2008-03-26 15:06 ` Segher Boessenkool
2008-03-26 15:40 ` Sergei Shtylyov
2008-03-27 9:24 ` Laurent Pinchart
2008-03-30 18:12 ` Segher Boessenkool
2008-03-26 15:09 ` Segher Boessenkool
2008-03-11 15:00 ` Rune Torgersen
2008-03-11 22:41 ` David Gibson
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