On Thu, Jan 29, 2015 at 03:58:42AM +0000, Suman Anna wrote:

On 01/22/2015 12:56 PM, Mark Rutland wrote:

quoted

On Wed, Jan 21, 2015 at 05:56:37PM +0000, Suman Anna wrote:

quoted

On 01/21/2015 06:41 AM, Ohad Ben-Cohen wrote:

quoted

On Tue, Jan 20, 2015 at 8:05 PM, Tony Lindgren [off-list ref] wrote:

quoted

How about default to Linux id space and allow overriding that with
a module param option if needed?

I'm not sure I'm following.

If the main point of contention is the base_id field, I'm also fine
with removing it entirely, as I'm not aware of any actual user for it
(Suman please confirm?).

Yeah, well the current implementations that I am aware of only have a
single bank, so all of them would be using a value of 0. I am yet to see
a platform with multiple instances where the property really makes a
difference. v7 has the property mandatory, so all the implementations
would need to define this value even if it is 0.

regards
Suman

quoted

Mark? Rob? Will you accept Suman's patches if the base_id field is removed?

My concern is that the mapping of hwspinlock IDs doesn't seem to be
explicit in the DT on a per-context basis, which is what I'd expect.

e.g.

lck: hwspinlock-device at f00 {
	...
	#hwlock-cells = <1>;
};

some-other-os-interface {
	...
	hwlocks = <&lck 0>, <&lck 1>, <&lck 2>, <&lck 3>;
	hwlock-names = "glbl", "pool0", "pool1", "pool2";
};

a-different-os-interface {
	...
	hwlocks = <&lck 18>, <&lck 21>, <&lck 4>, <&lck 5>;
	hwlock-names = "init", "teardown", "pool0", "pool1";
};

That's the only way I would expect this to possibly remain a stable
over time, and it's the entire reason for #hwlock-cells, no?

How do you expect the other components sharing the hwspinlocks to be
described?

Yes indeed, this is what any of the clients will use on Linux. But
this is not necessarily the semantics for exchanging hwlocks with the
other processor(s) which is where the global id space comes into
picture.

I did try to consider that above. Rather than thinking about the
numbering as "global", think of it as unique within the a given pool
shared between processors. That's what the "poolN" names are about
above.

That way you can dynamically allocate within the pool and know that
Linux and the SW on the other processors will use the same ID. You can
have pools that span multiple hwlock hardware blocks, and you can have
multiple separate pools in operation at once.

Surely that covers the cases you care about?

If using names is clunky, we could instead have a pool-hwlocks property
for that purpose.

Thanks,
Mark.