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Re: Fixes to MTD flash driver on AMD Alchemy db1100 board

To: Ulrich Eckhardt <eckhardt@satorlaser.com>
Subject: Re: Fixes to MTD flash driver on AMD Alchemy db1100 board
From: Josh Green <jgreen@users.sourceforge.net>
Date: Mon, 21 Feb 2005 15:57:55 -0800
Cc: linux-mips@linux-mips.org
In-reply-to: <200502211144.58470.eckhardt@satorlaser.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1108962105.6611.24.camel@SillyPuddy.localdomain> <200502211144.58470.eckhardt@satorlaser.com>
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On Mon, 2005-02-21 at 11:44 +0100, Ulrich Eckhardt wrote:
> Disclaimer: I'm far from being a kernel expert, so if I'm talking crap 
> somebody please enlighten me. I just looked at the code and saw what to me 
> looked inconsistent.
> 

I'm no kernel expert either, so no comments from me :)

> > I can see the partitions in /dev/mtd now, but I have not thoroughly
> > tested it yet to see if there are any other problems.
> 
> Can you tell me how you created /dev/mtd? My version (Debian/x86) of MAKEDEV 
> doesn't know these. Also, could you tell me how you configured your kernel? I 
> have never seen an MTD working, so I don't even know if what I'm doing is 
> supposed to work. :(
> 

I used a CVS checkout of buildroot from linux-mips.org to build my
initial cross compile x86->mips tool chain and root file system.  I'm
now building most of the software separately (kernel, busybox, hostap,
wireless-tools, wavemon, pcmcia-cs, etc) since I've found it to be more
flexible.  So to answer your question, buildroot made the device files
for me.  You could easily create them though using mknod:

mknod /dev/mtdblock0 b 31 0
mknod /dev/mtdblock1 b 31 1
mknod /dev/mtdblock2 b 31 2
mknod /dev/mtdblock3 b 31 3

You could do the same for the mtd0-3 devices, although I don't have use
for them myself.  They are major 90, minor 0, 2, 4, 6 for mtd0,1,2,3
respectively.

Another note concerning the MTD stuff.  It did not work for me until I
enabled some chip drivers in the RAM/ROM/Flash chip drivers section,
specifically:
<*> Detect flash chips by Common Flash Interface (CFI) probe
<*> Support for AMD/Fujitsu flash chips

Some additional options I have enabled in the MTD section:
[*] MTD partitioning support
<*> MTD concatenating support  (I think this is might be needed for the
case where you enable both user and boot chips, but I wouldn't be
surprised if I'm wrong about that)
<*> Caching block device access to MTD devices

Once I had that enabled I now see the "user FS", "kernel", "yamon" MTD
partitions in the kernel dmesg output.


> Uli
> 
> 


I am now building a compressed kernel (using some patches I found from
Pete Popov in a mailing list archive here:
http://www.spinics.net/lists/mips/msg18196.html) and have successfully
flashed and booted it by copying it to the correct mtdblock device.

I've also got jffs2 working on the User FS partition, but I get a whole
bunch of errors when it boots (regardless it still seems to function).
I'll post these in another thread if I can't get it resolved.


Best regards,
        Josh Green

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