Albrecht Dreß wrote:
> Hi all,
>
> I ran into a weird problem when I tried to access a static (NV) ram attached
> 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. the
> of entry reads
>
> nv...@1,0 {
> compatible = "mtd-ram";
> reg = <1 0x0 0x00080000>; // 512 kB
> bank-width = <2>;
> device-width = <2>;
> #size-cells = <1>;
> #address-cells = <1>;
> };
>
> For the test I created a "pattern file" which is filled with the unsigned
> long 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 (write
> 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=pattern of=/dev/mtd5 bs=512" the dword's at
> offset 0x1fc, 0x3fc, ... are 0x0000aaaa (instead of 0x0055aaff), if I use
> bs=1024 the dwords at 0x3fc, 0x7fc, ... show this value, if I use bs=4096 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 should be fine, as
> u-boot uses the same as Linux.
>
> Any idea what goes wrong here? I guessed I missed something in the LPB
> setup...
Check your cache setup - the BDI is most certainly not accessing
this via the Data cache whereas Linux probably will be.
--
------------------------------------------------------------
Gary Thomas | Consulting for the
MLB Associates | Embedded world
------------------------------------------------------------
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@ozlabs.org
https://ozlabs.org/mailman/listinfo/linuxppc-dev
