[PATCH v3 5/5] ARM: vexpress: DT-based support for CoreTiles Express A5x2 and A9x4

On Mon, Dec 05, 2011 at 05:47:36PM +0000, Pawel Moll wrote:

On Mon, 2011-12-05 at 17:37 +0000, Dave Martin wrote:

quoted

quoted

I have an idea of spinning the compatible values again to get something
like that:

compatible = "arm,vexpress-v2p-ca5s", "arm,vexpress-cortex_a5";
compatible = "arm,vexpress-v2p-ca9", "arm,vexpress-cortex_a9";
compatible = "arm,vexpress-v2p-ca15", "arm,vexpress-cortex_a15";

The trouble is, node { compatible = x } means "node is an x", not "node
has an x".

Yes...

quoted

So, we should be careful do document what e.g. arm,vexpress-cortex_a5
actually means.  It doesn't mean Cortex-A5, but instead it represents
a whole jumble of characteristics which we expect to be common to all
vexpress-based A5 platforms.

... so I'd translate it as "is a Versatile Express platform based on
Cortex-A5 processor" and document it as such. As I said - patches
tomorrow.

quoted

It feels that in practice arm,vexpress-cortex_a5 actually means 
exactly the same thing as arm,vexpress-v2p-ca5s.  Are you sure these
two are really independent?  (In other words, do we expect multiple
different vexpress variants based on A5, and so on?)

The examples for A5 I can quota are two different SMMs I used (one on a
"small", second one on a "large" FPGA board), but they were very similar
to the A5 core tile - so similar that you could (probably) use the core
tile DTB to drive them. The A9 SMM with RS1 memory map I've mentioned is
much more interesting case - A9 platform but nothing like original A9
core tile... Also the A15 looks interesting as we will most likely get
the same tiles (as in: PCB) with different processors (as in: different
silicon). This will be fun :-)

OK -- your knowledge of what's going on in hardware-land is better than
mine, so I'm happy to go along with this.

So long as those compatible strings are carefully documented to that
their meanings don't get blurred over time, your proposal seems to make
sense.

Cheers
---Dave