timur at freescale.com
Tue Apr 28 23:48:47 EST 2009
David Gibson wrote:
> On Wed, Apr 22, 2009 at 11:41:31PM -0500, Kumar Gala wrote:
>> Lets say I had an error driver for our MCM (core to soc coherency
>> module). It was getting the base address by using get_immrbase().
>> Today I proposed a proper device node for the MCM block as it doesn't
>> exist in .dts today. We add such a node into .dts and I can clean up my
>> error driver to use proper device node information. However I've just
>> broken any old .dts that didn't have this node. You are saying I need to
>> add code into the kernel to create this new node and we have to keep that
>> code around for ever in the kernel.. why would I ever bother to actually
>> changing anything than.
> Well, again. It's a judgement call, balancing the pain of having to
> update the dts files (which depends on how widely deployed the
> platform is) versus the pain of having to keep the bacwards
> compatibility shim in the kernel.
I agree with this sentiment. I'm only asking for a reasonable attempt
at adding backwards compatibility via an isolated code block. Sprinkle
in a few comments, and that should be enough. It won't always be
possible to add such code, but at the very least, I expect the
driver/kernel to clearly indicate what's missing from the device tree.
In Kumar's example above, I expect the kernel to say that the MCM node
Linux kernel developer at Freescale
More information about the Linuxppc-dev