"Chemparathy, Cyril" <[email protected]> writes:

> Hi Kevin,
>
>> > If so, the only requirement on this should be that this "register"
>> > have the same address across all davinci derivatives.
>> >
>> > EDMA is the only module that meets this criterion, since it is
>> > consistently present @ 0x01c00000 across all socs (so far).
>> 
>> That seems like a reasonable option since we can assume that EDMA is
>> disabled during early uncompress/boot.
>> 
>> Maybe the channel src or dest regs?
>
> The only problem is that EDMA CC will need to be brought out of
> reset either in the uncompress init code or in the bootloader.

Good point, that would be a bit clumsy to do in an SoC independent way
in the uncompress code.

> Wouldn't it be cleaner to use a few words of memory between the boot
> params and zreladdr?  For example, 16 bytes @0x80007ff0 can be used
> to pass in uart phys, virt, and shift.  This should work cleanly
> across socs, and is less dependent on MMR layout should some future
> architecture change things.

That's worth a try.

Just make sure you copy the values out after first read since that
first page will be unmapped early in boot.  The OMAP debug-macros.S
does this as an example.

Kevin

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