Grant Likely wrote:
> On 10/25/07, Martin Krause <[EMAIL PROTECTED]> wrote:
>>
>> < + [EMAIL PROTECTED] {
>> < + compatible = "cfi-flash";
>> < + reg = <00000000 02000000>;
>> < + bank-width = <4>;
>> < + device-width = <2>;
>> < + #size-cells = <1>;
>> < + #address-cells = <1>;
>> < + [EMAIL PROTECTED] {
>> < + label = "firmware";
>> < + reg = <0 a0000>;
>> < + };
>> < + [EMAIL PROTECTED] {
>> < + label = "dtb";
>> < + reg = <a0000 20000>;
>> < + };
>> < + [EMAIL PROTECTED] {
>> < + label = "kernel";
>> < + reg = <c0000 240000>;
>> < + };
>> < + [EMAIL PROTECTED] {
>> < + label = "initrd";
>> < + reg = <300000 200000>;
>> < + };
>> < + [EMAIL PROTECTED] {
>> < + label = "small-fs";
>> < + reg = <500000 400000>;
>> < + };
>> < + [EMAIL PROTECTED] {
>> < + label = "misc";
>> < + reg = <900000 800000>;
>> < + };
>> < + [EMAIL PROTECTED] {
>> < + label = "big-fs";
>> < + reg = <1100000 f00000>;
>> < + };
>> < + };
>> < + };
>>
>> This MTD layout only works on boards with 32 MiB (or 64 MiB) flash
>> memory. On TQM5200 boards with smaller Flashes (16 MiB, 8 MiB and 4 MiB)
>> the MTD partition borders do not match with the physikal memory borders.
>
> If there is a variant board with a different configuration, then the
> device tree needs to be changed for that variant board; either by
> having multiple .dts files in arch/powerpc/boot/dts or by having the
> bootloader populate the correct information. A dtb as passed to the
> kernel must exactly represent the hardware.
>
> That also means that there is going to be a different flash map for
> each possible flash size configuration.
Agree, that's one particular configuration (I guess I should add
proper comment), that should be updated if needed. But I'am not sure
if we should have multiple .dts files if it's only flash layout that
changes.
>> On a board with 16 MiB FLASH for example the "big-fs" _and_ the "misc"
>> partition could not be used. "big-fs", because the memory is too small
>> (which is OK) and "misc", because it overlaps 1 MiB over the physikal
>> flash border. So only the first 9 MiB of the flash could be used in Linux.
>> The remaining 7 MiB couldn't be accessed.
>
> Perhaps it would be better to drop the flash layout from the in-kernel
> dts files entirely since flash layout can be a fluid thing.
Well, but that would not be really user friendly, I'd rather stick
with some default config.
m.
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