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    SubjectRe: [PATCH v3 0/5] common clk framework
    On Tue, Nov 22, 2011 at 9:45 AM, Russell King - ARM Linux
    <> wrote:
    > On Tue, Nov 22, 2011 at 07:42:59AM -0800, Greg KH wrote:
    >> On Mon, Nov 21, 2011 at 05:40:42PM -0800, Mike Turquette wrote:
    >> >   .sysfs support.  Visualize your clk tree at /sys/clk!  Where would be
    >> > a better place to put the clk tree besides the root of /sys/?
    >> Um, in the "proper" place for it under /sys/devices like the rest of the
    >> device tree is?
    > I'd suggest that making the clock tree visible in sysfs (and therefore
    > part of the kernel ABI) is not a good idea.  Some of the nodes in there
    > will be specific to the implementation.  Exposing the clock nodes means
    > that if you have to change the clock tree structure, you change the
    > visible userspace ABI.

    It is true that the ABI will change dynamically.

    > So, I'd suggest that we need to see a justification for this, rather
    > than exposing this stuff via debugfs as has been done with existing
    > implementations.

    Userspace tools like powerdebug (and maybe someday powertop) hope to
    use a reliable-looking interface to view clk data. There are obvious
    uses for this data in a debug tool, the most obvious of which is
    "which clk isn't turning off when it should?".

    I can migrate this stuff to debugfs, but it adds the burden of having
    debugfs enabled for folks that want to view this data. I would also
    argue that sysfs is there to model various aspects of system topology
    and a clk tree certainly fits the bill.

    If others also agree that it should reside only in debugfs then I'll
    move it there for V4.

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