Re: [RFC/PATCH 1/3] powerpc: add ioremap_bat() function for setting up BAT translated IO regions.

Kumar Gala wrote:

On Aug 6, 2008, at 4:54 PM, Grant Likely wrote:

quoted

I suppose we could; but the usecase is somewhat different and I
wanted to keep it simple.  Using a separate API also helps
reenforce that the caller really needs to know what they are doing
because BATs are a limited resource.

there is a bunch of error checking and difference in semantics that
you need to fix.  I think introduce a new API for this is silly,

Why is it silly?  It seems silly to me to complicate ioremap() with knowing when to use BATs and when not to use them.

especially since we expect there to only be one actual invocation of
the API for serial console access.

I could also see a BAT (or equivalent) being used for IMMR-space, or
other frequently accessed registers, to save TLB entries.

-Scott