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From: "Albrecht Dreß" <albrecht.dress@arcor•de>
To: linuxppc-dev@ozlabs•org
Subject: Weird 5200/mtd-ram problem
Date: Wed, 20 May 2009 16:13:05 +0200 (CEST)	[thread overview]
Message-ID: <14558983.1242828785546.JavaMail.ngmail@webmail10.arcor-online.net> (raw)

Hi all,

I ran into a weird problem when I tried to access a static (NV) ram attache=
d to the localbus of a '5200 using Wolfram's mtd-ram OF driver (on a stock =
2.6.29.1 kernel).  The 512k ram chip is connected in 16-bit mode to cs1.  t=
he of entry reads

nvram@1,0 {
=09compatible =3D "mtd-ram";
=09reg =3D <1 0x0 0x00080000>;      // 512 kB
=09bank-width =3D <2>;
=09device-width =3D <2>;
=09#size-cells =3D <1>;
=09#address-cells =3D <1>;
=09};

For the test I created a "pattern file" which is filled with the unsigned l=
ong 0x0055aaff.  Using the Abatron BDI3000, I can write the pattern file to=
 the ram and re-read it without problems.  The same applies to u-boot (writ=
e ram via tftp, dump contents).

In Linux, when I write the file to /dev/mtdx, the last dword of each block =
is broken, e.g. when running "dd if=3Dpattern of=3D/dev/mtd5 bs=3D512" the =
dword's at offset 0x1fc, 0x3fc, ... are 0x0000aaaa (instead of 0x0055aaff),=
 if I use bs=3D1024 the dwords at 0x3fc, 0x7fc, ... show this value, if I u=
se bs=3D4096 the dword at 0xffc shows this value, etc.  I looked at the CS/=
WR lines with a scope, and I couldn't see anything special.  The timing sho=
uld be fine, as u-boot uses the same as Linux.

Any idea what goes wrong here?  I guessed I missed something in the LPB set=
up...

Thanks in advance,
Albrecht.

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next             reply	other threads:[~2009-05-20 14:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-20 14:13 Albrecht Dreß [this message]
2009-05-20 14:23 ` Weird 5200/mtd-ram problem Gary Thomas
2009-05-20 19:36   ` Albrecht Dreß
2009-05-20 19:59     ` Gary Thomas
2009-05-20 20:01 ` Wolfram Sang
2009-05-25 17:41   ` Albrecht Dreß
2009-05-25 18:11     ` Wolfgang Denk
2009-05-25 21:47     ` Wolfram Sang
2009-05-27 19:54       ` [Solved/Patch Question] " Albrecht Dreß
2009-05-28  3:10         ` Jon Smirl

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