From: Sergei Shtylyov <sshtylyov@ru•mvista.com>
To: Wolfgang Grandegger <wg@grandegger•com>
Cc: linuxppc-embedded@ozlabs•org
Subject: Re: Flat device tree definitions for FLASH and MTD partitioning
Date: Thu, 26 Apr 2007 16:36:41 +0400 [thread overview]
Message-ID: <46309CD9.1050403@ru.mvista.com> (raw)
In-Reply-To: <4630611C.4060902@grandegger.com>
Hello.
Wolfgang Grandegger wrote:
>>>>>>>> are there already some thought or even example code on how to
>>>>>>>> define Flash memory and MTD partitions in the DTS. This would
>>>>>>>> avoid the ackward MTD partitioning via static structure or boot
>>>>>>>> line argument and could be done in a generic way.
>>>>>>> See Documentation/powerpc/booting-without-of.txt and
>>>>>>> drivers/mtd/physmap_of.c for what's been already done.
>>>>>> I meant drivers/mtd/maps/physmap_of.c
>>>>> I had a closer look to this driver. Unfortunately, it can not
>>>>> handle yet multiple FLASH banks. This could be achieved with an
>>>>> additional property "bank_count". What do you think?
>> Please use hyphen, not underscore in property names ("device_type"
>> seems an only exception from this rule).
> Yes, I know and I also wondered why an "_" is used for the device type.
Ask the OF spec. developers. :-)
>>>> I'm not sure what banks you're talking about -- note that this
>>>> driver is equivalen in functionality to the plain 'physmap' driver
>>>> and there's inherited "bank-width" property that handles flash banking.
>>> Yes, I know. Nevertheless the driver cannot handle flash regions
>>> composed of more than on FLASH bank because we need to probe every
>>> bank. Search for "BANK" in drivers/mtd/maps" to understand what I mean.
>> Hm, from what I could see, those banks are separate maps registered
>> to MTD subsys separately.
>> What's the point of adding a count property when we simply can define
>> multiple "rom" devices?
> To complete this thread, physmap_of can map _one_ FLASH region composed
> of one or more FLASH banks. But it currently cannot map more than _one_
> FLASH region.
I wodner why?! :-O
> It would be nice to extend it for multiple FLASH
> definitions (could code it when time permits).
I'm seeing nothing that prevents it from working now -- it should register as much "rom" devices as you supply via the device tree.
> Wolfgang.
MBR, Sergei
next prev parent reply other threads:[~2007-04-26 12:35 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-08 11:37 Flat device tree definitions for FLASH and MTD partitioning Wolfgang Grandegger
2007-04-08 12:11 ` Sergei Shtylyov
2007-04-08 12:21 ` Sergei Shtylyov
2007-04-08 12:41 ` Wolfgang Grandegger
2007-04-25 12:55 ` Wolfgang Grandegger
2007-04-25 13:35 ` Sergei Shtylyov
2007-04-25 14:02 ` Wolfgang Grandegger
2007-04-25 14:34 ` Sergei Shtylyov
2007-04-25 18:57 ` Wolfgang Grandegger
2007-04-26 8:21 ` Wolfgang Grandegger
2007-04-26 12:36 ` Sergei Shtylyov [this message]
2007-04-26 12:59 ` Wolfgang Grandegger
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