On 10/18/2012 08:54 AM, Russell King - ARM Linux wrote:

On Thu, Oct 18, 2012 at 08:47:56AM -0500, Rob Herring wrote:

quoted

Here is what I mentioned previously. This removes the static mapping from 
the platforms. This is untested and probably breaks on different DEBUG_LL 
options. For now, platforms call debug_ll_io_init, but once all platforms 
are converted, this can be called from devicemaps_init.

There's a problem with this approach.  What if the platform specifically
sets the debug addresses to be within one of it's existing mappings (which
is definitely what you'd want to do with 8250-based UARTs attached to a
PCI bus.)

This isn't going to work in that case unless we split the debug mapping
from the PCI IO space mapping.

It is opt-in, so we may never get to the last step. We're still better
off than now. Is there a platform that is doing this? If so, I didn't
move any DEBUG_LL users to the fixed i/o space so they would still be
using their old i/o space address. Having 2 mappings would work, right?
You use the debug mapping initially and when PCI bus and the real
console driver are up, you switch to the fixed i/o space.

This isn't just a PCI issue. You could also have a mapping that covers a
block of SOC peripherals including the uart and you don't want a
separate mapping.

Rob