[RFC PATCH] ARM: mvebu: Let the device-tree determine smp_ops

Chris Packham Chris.Packham at alliedtelesis.co.nz
Thu Nov 6 11:49:22 PST 2014

On 11/07/2014 03:49 AM, Andrew Lunn wrote:
> On Thu, Nov 06, 2014 at 05:49:56PM +1300, Chris Packham wrote:
>> The machine specific SMP operations can be configured either via
>> setup_arch or via arm_dt_init_cpu_maps. For the ARMADA_370_XP_DT devices
>> both of these are called and setup_arch wins because it is called last.
>> This means that it is not possible to substitute a different set of SMP
>> operations via the device-tree.
>> All of the ARMADA_370_XP_DT compatible devices are either single core or
>> declare an enable-method in the dts (via one of armada-xp-mv78230.dtsi,
>> armada-xp-mv78260.dtsi or armada-xp-mv78460.dtsi). Remove the smp
>> assignment from board-v7.c so that the SMP operations set via the
>> device-tree aren't discarded.
>> Signed-off-by: Chris Packham <chris.packham at alliedtelesis.co.nz>
>> ---
>> Hi,
>> (This is the first patch I've sent to the arm-lkml so beware of my newbie-ness)
> Hi Chris
> Congratulations on a good looking patch. Nice changelog, has a
> signed-off-by, comments are bellow the ---. All good.
> It is however a good idea to Cc: the mvebu maintainers. I added a few
> people to Cc:.
Thanks for the warm welcome. I actually thought the same thing after I 
hit send, thanks for filling in the Cc list for me.
>> I'm working on a new board that uses a integrated CPU that according to the
>> vendor is "based on the ARMADA-XP", more on that to come in the future
>> hopefully.
> A packet processor chip with an embedded CPU? Next generation
> Prestera?  No need to answer that if you don't want to.
You guess correctly. Not sure how much I can say without falling foul of 
our NDA but they know I intend on trying to get this stuff upstream 
rather than being locked into their particular SDK.
>> For the most part things just work if I use a .dts based on the
>> mv78260.
>> This is my attempt at fixing the problem by not setting mdesc.smp for the
>> ARMADA_370_XP_DT machines thus preventing setup_arch from overriding what has
>> been setup by arm_dt_init_cpu_maps.
> You really need Thomas or Gregory to Ack this patch, but to me it
> looks correct.  Interestingly, this machine descriptor is used by 370,
> which is a single processor. The smp operations are useless, so your
> patch is also partly a cleanup.
>       Andrew

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