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 20:37:42 +0300 [thread overview]
Message-ID: <47E93866.1060606@ru.mvista.com> (raw)
In-Reply-To: <200803251823.32039.laurentp@cse-semaphore.com>
Laurent Pinchart wrote:
>>>>Heh, there was a whole company against mentioning "mtd" when we started
>>>>working on this (of course, the first idea was to call the flash device
>>>>type "mtd"). I don't think "mtd" looks good here -- I'd suggest
>>>>"flash-ram" (if this is just a linearly mapped NVRAM).
>>>I'm fine with "flash-ram" (even thought it looks a bit weird). I'll
>>>prepare a patch.
>>Yeah. I forgeot that "flash" means EEPROM. Actually, the main facts about
>>the NVRAM that I'd want to be stated in the "compatible" property is that
>>it's non-volatile and directly/lineraly mapped... Just "nvram" doesn't seem
>>enopugh, maybe "linear-nvram" is.
> Direct mapping is a hard requirement for the nvram if we want to use it with
> the MTD subsystem.
I thought we're currently talking about a driver controlling the directly
mapped NVRAM. The "compatible" property wouldn't allow us to specify the
compatibility to *any* NVRAM since there could be no "least common
denominator" driver anyway.
> Regarding non-volatility nothing prevents a user from
> using a volatile RAM as an MTD device, but there's little point in doing so.
Indeed, if just for testing... we could specify non-volatility as the
device's prop, though...
> Would it be acceptable for the "linear-nvram" specification not to include
> volatile RAM ? ROM chips would be excluded too. Is that an issue ?
Well, I think we need a separate "compatible" prop for ROMs. Or we'll end
up with the "compatible" being just "memory" with the memory "attributes"
(R/O, N/V) being described by other "properties"... :-)
>>And we can specify "device_type" of "nvram" indeed (and #size).
> I suppose you meant #bytes.
Of course. :-)
> What about sub-partitions support ? Nothing prevents RAM-based MTD devices
Hm... I remember that the knowledge of MTD partitions turned me away from
"nvram" device type when I started spec'ing the flash binding -- it's not
uncommon to have a flash partition devoted to and labelled as "nvram".
Therefore, that sole partition would have been a "nvram" device for OF...
> from being partioned. Would it be acceptable to reference the CFI/JEDEC flash
> section in Documentation/powerpc/booting-without-of.txt in the description of
> the nvram node ?
I don't see why not.
> Best regards,
WBR, Sergei
next prev parent reply other threads:[~2008-03-25 17:36 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=47E93866.1060606@ru.mvista.com \
--to=sshtylyov@ru$(echo .)mvista.com \
--cc=ben@simtec$(echo .)co.uk \
--cc=david@gibson$(echo .)dropbear.id.au \
--cc=laurentp@cse-semaphore$(echo .)com \
--cc=linux-mtd@lists$(echo .)infradead.org \
--cc=linuxppc-dev@ozlabs$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox