Weird 5200/mtd-ram problem

["Albrecht Dreß" <albrecht.dress@arcor.de>]

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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