From: Sergei Shtylyov <sshtylyov@ru•mvista.com>
To: Segher Boessenkool <segher@kernel•crashing.org>
Cc: linuxppc-dev@ozlabs•org, linux-mtd@lists•infradead.org,
Milton Miller <miltonm@bga•com>
Subject: Re: [PATCH] powerpc: Create "rom" (MTD) device prpmc2800
Date: Mon, 04 Jun 2007 17:34:08 +0400 [thread overview]
Message-ID: <466414D0.4090403@ru.mvista.com> (raw)
In-Reply-To: <193459b778ff98aa95ee7ac38a842c16@kernel.crashing.org>
Hello.
Segher Boessenkool wrote:
>>>>> This has nothing to do with a "chip level", it is plain and
>>>>> simply the most basic device tree stuff.
>>>> If it was as "plain and simple" as you say, there would be
>>>> nothing to argue about.
>>> There isn't as far as I am concerned; the purpose and
>>> meaning of the "compatible" property, as well as of any
>>> other standard OF properties, is clear.
>> Erm, concerning matching those with drivers it wasn't as clear that
>> those props aren't the same as driver names b/c of the follwing
>> passage in Generic Names:
> [huge snip]
> Please point out the exact passage you don't understand, and
> what you don't understand about it, if you want any help.
Ah, nevermind... It was too late in the Sunday evening. :-)
>>> Yes, the more complex (and sometimes insane) ways that
>>> flash chips are connected to systems can be really hard
>>> to describe properly. Which is why I don't even want
>>> to make a "binding" for it (yet). It seems easy enough
>> Neither do we. :-)
>>> to do this for single flash chips (possibly direct-mapped)
>>> though.
>> Erm, FSL boards seem to generally have dual 16-bit NOR flash chips
>> interleaved -- and that's seems quite a common case, not only in PPC
>> world.
> It's not all that common; I can see why it would be used on
> flash controllers that handle a 32-bit bus only.
OK, maybe it's just we, embedded guys, that comes to see only such cheapo
boards. :-)
>> Perhaps... those interleaved chips could really be merged
>> (abstracted) into a single one, with the bus width being a sum of two?
> Perhaps. It is a nasty situation, it'll take long hard
> thinking to come up with a reasonably good solution.
I hoped to get some hints from the linux-mtd list as well...
>>> Get the simple cases
>>> (that actually are used in real life) right, first.
>> We pursued this task exactly. Get it working, quick. :-)
> That is something *TOTALLY DIFFERENT* and quite a bad plan
> IMNSHO.
I haven't considered 2 inteleaved 16-bit CFI NOR flashes a complex case so
far, sorry. :-) And that's what I had on my board. Prior to my acquaintance
with the device trees, this was indeed a no-brainer. :-)
> Segher
WBR, Sergei
next prev parent reply other threads:[~2007-06-04 13:32 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-02 4:30 [PATCH] powerpc: Create "rom" (MTD) device prpmc2800 Milton Miller
2007-06-02 7:39 ` Benjamin Herrenschmidt
2007-06-03 16:10 ` Sergei Shtylyov
2007-06-03 17:36 ` Segher Boessenkool
2007-06-03 18:03 ` Sergei Shtylyov
2007-06-03 18:25 ` Segher Boessenkool
2007-06-03 18:36 ` Sergei Shtylyov
2007-06-03 18:46 ` Segher Boessenkool
2007-06-03 19:16 ` Sergei Shtylyov
2007-06-03 21:04 ` Benjamin Herrenschmidt
2007-06-04 12:34 ` Sergei Shtylyov
2007-06-04 14:37 ` Segher Boessenkool
2007-06-04 14:49 ` Sergei Shtylyov
2007-06-07 14:53 ` David Woodhouse
2007-06-07 15:49 ` Segher Boessenkool
2007-06-07 14:47 ` David Woodhouse
2007-06-07 15:32 ` Segher Boessenkool
2007-06-02 8:53 ` Segher Boessenkool
2007-06-03 16:22 ` Sergei Shtylyov
2007-06-03 17:40 ` Segher Boessenkool
2007-06-03 18:31 ` Sergei Shtylyov
2007-06-03 18:44 ` Segher Boessenkool
2007-06-03 19:13 ` Sergei Shtylyov
2007-06-03 19:56 ` Segher Boessenkool
2007-06-03 20:26 ` Sergei Shtylyov
2007-06-04 8:07 ` Segher Boessenkool
2007-06-04 13:34 ` Sergei Shtylyov [this message]
2007-06-07 15:00 ` David Woodhouse
2007-06-07 15:55 ` Segher Boessenkool
2007-06-07 16:05 ` David Woodhouse
2007-06-07 16:46 ` Segher Boessenkool
2007-06-12 4:44 ` David Gibson
2007-06-12 10:53 ` Segher Boessenkool
2007-06-13 3:16 ` David Gibson
2007-06-13 5:05 ` Segher Boessenkool
2007-06-13 6:11 ` David Gibson
2007-06-13 9:10 ` Segher Boessenkool
2007-06-15 4:12 ` David Gibson
2007-06-15 11:22 ` Segher Boessenkool
2007-06-15 4:14 ` David Gibson
2007-06-15 8:42 ` Segher Boessenkool
2007-06-15 8:47 ` David Woodhouse
2007-06-15 8:59 ` Segher Boessenkool
2007-06-03 21:12 ` Benjamin Herrenschmidt
2007-06-04 8:11 ` Segher Boessenkool
2007-06-04 13:16 ` Sergei Shtylyov
2007-06-04 12:41 ` Sergei Shtylyov
2007-06-04 14:49 ` Segher Boessenkool
2007-06-04 15:54 ` Sergei Shtylyov
2007-06-03 17:29 ` Sergei Shtylyov
2007-06-03 17:45 ` Segher Boessenkool
2007-06-03 18:18 ` Sergei Shtylyov
2007-06-03 18:43 ` Segher Boessenkool
2007-06-03 18:59 ` Sergei Shtylyov
2007-06-03 19:48 ` Segher Boessenkool
2007-06-03 20:10 ` Sergei Shtylyov
2007-06-04 8:02 ` Segher Boessenkool
2007-06-04 19:40 ` Mark A. Greer
-- strict thread matches above, loose matches on Subject: below --
2007-06-01 23:20 Mark A. Greer
2007-06-02 8:46 ` Segher Boessenkool
2007-06-04 20:56 ` Mark A. Greer
2007-06-05 20:35 ` Sergei Shtylyov
2007-06-05 21:11 ` Mark A. Greer
2007-06-06 12:41 ` Sergei Shtylyov
2007-06-07 15:08 ` David Woodhouse
2007-06-06 2:39 ` David Gibson
2007-06-07 13:30 ` Segher Boessenkool
2007-06-12 4:42 ` David Gibson
2007-06-12 10:50 ` Segher Boessenkool
2007-06-13 6:12 ` David Gibson
2007-06-13 9:13 ` Segher Boessenkool
2007-06-13 9:19 ` David Gibson
2007-06-13 9:37 ` Segher Boessenkool
2007-06-14 4:29 ` David Gibson
2007-06-14 8:00 ` Segher Boessenkool
2007-06-14 12:39 ` Sergei Shtylyov
2007-06-14 13:20 ` Segher Boessenkool
2007-06-14 12:48 ` Sergei Shtylyov
2007-06-14 13:18 ` Segher Boessenkool
2007-06-14 12:50 ` Sergei Shtylyov
2007-06-14 13:43 ` Segher Boessenkool
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