Hi!

On Fri, May 31, 2019 at 11:03:26AM +1000, Benjamin Herrenschmidt wrote:

On Thu, 2019-05-30 at 14:37 -0500, Segher Boessenkool wrote:

quoted

On Thu, May 30, 2019 at 05:09:06PM +1000, Alexey Kardashevskiy wrote:

quoted

so, it is sort-of nack from David and sort-of ack from Segher, what
happens now?

Maybe what we really need just a CI call to get all properties of a node
at once?  Will that speed up things enough?

That way you need no change at all in lifetime of properties and how they
are used, etc.; just a client getting the properties is a lot faster.

Hrm... if we're going to create a new interface, let's go for what we
need.

What we need is the FDT. It's a rather ubiquitous thing these days, it
makes sense to have a way to fetch an FDT directly from FW.

That is all you need if you do not want to use OF at all.

If you *do* want to keep having an Open Firmware, what we want or need
is a faster way to walk huge device trees.

There is no use for the "fetch all properties" cases other than
building an FDT that any of us can think of, and it would create a more
complicated interface than just "fetch an FDT".

It is a simple way to speed up fetching the device tree enormously,
without needing big changes to either OF or the clients using it -- not
in the code, but importantly also not conceptually: everything works just
as before, just a lot faster.

So I go for the simple one and agree with Alexey's idea.

When dealing with a whole device tree you have to know about the various
dynamically generated nodes and props, and handle each appropriately.


Segher