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    SubjectRe: [PATCH v2 2/6] of: Add helper for mapping device node to logical CPU number
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    On 25/07/17 10:27, Suzuki K Poulose wrote:
    > On 24/07/17 17:42, Sudeep Holla wrote:
    >>
    >>
    >> On 24/07/17 11:29, Suzuki K Poulose wrote:
    >>> Add a helper to map a device node to a logical CPU number to avoid
    >>> duplication. Currently this is open coded in different places (e.g
    >>> gic-v3, coresight). The helper tries to map device node to a "possible"
    >>> logical CPU id, which may not be online yet. It is the responsibility
    >>> of the user to make sure that the CPU is online. The helper uses
    >>> of_get_cpu_node() which uses arch specific backends to match the
    >>> phyiscal
    >>> ids.
    >>>
    >>> Cc: Rob Herring <robh+dt@kernel.org>
    >>> Cc: Mark Rutland <mark.rutland@arm.com>
    >>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    >>> ---
    >>> drivers/of/base.c | 26 ++++++++++++++++++++++++++
    >>> include/linux/of_device.h | 7 +++++++
    >>> 2 files changed, 33 insertions(+)
    >>>
    >>> diff --git a/drivers/of/base.c b/drivers/of/base.c
    >>> index 686628d..639af23 100644
    >>> --- a/drivers/of/base.c
    >>> +++ b/drivers/of/base.c
    >>> @@ -420,6 +420,32 @@ struct device_node *of_get_cpu_node(int cpu,
    >>> unsigned int *thread)
    >>> EXPORT_SYMBOL(of_get_cpu_node);
    >>>
    >>> /**
    >>> + * of_device_node_get_cpu: Get the logical CPU number for a given
    >>> device_node
    >>> + *
    >>> + * @cpu_node: Pointer to the device_node for CPU.
    >>> + *
    >>> + * Returns the logical CPU number of the given CPU device_node.
    >>> + * Returns >= nr_cpu_ids if CPU is not found.
    >>> + */
    >>> +int of_device_node_get_cpu(struct device_node *cpu_node)
    >>> +{
    >>> + int cpu, thread;
    >>> + bool found = false;
    >>> + struct device_node *np;
    >>> +
    >>> + for_each_possible_cpu(cpu) {
    >>> + np = of_get_cpu_node(cpu, &thread);
    >>
    >> Ideally, we should be able to use of_cpu_device_node_get instead of
    >> of_get_cpu_node which parses the device tree. Not sure if that's the
    >> case here too.
    >>
    >> Sorry for following up on this so late. I had a patch in my tree
    >> for-a-while to address that. Just posted it[1] now seeing this patch now.
    >>
    >> You can move to of_cpu_device_node_get if all users of this function are
    >> called after CPU's are registered. Otherwise, you can keep it as is for
    >> now and it can be changed once [1] lands.
    >
    > As you mentioned offline, since GIC uses this, we need to stick to
    > of_get_cpu_node.

    Agreed.

    > In fact, I started off with the of_cpu_device_node_get() and switched
    > to the former.
    >

    Ah OK.

    > It would be really nice to have your patch, which streamlines the
    > interface and we could switch to that.
    >

    Yes, I will wait for that patch to land in the mainline, I can follow up
    and remove the use of of_get_cpu_node wherever required.
    --
    Regards,
    Sudeep

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