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    SubjectRe: [PATCH 1/3] ASoC: ti: omap-mcbsp: Ignore errors for getting fck_src
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    On 07/10/2023 10:11, Andreas Kemnade wrote:
    >> OK good to hear it works, I'll send out fixes for omap4 and 5, seems
    >> the runtime PM warning is something different.
    >>
    >>> omap-mcbsp 40124000.mcbsp: Runtime PM usage count underflow!
    >>> # cat /sys/bus/platform/devices/40124000.mcbsp/power/runtime_status
    >>> active
    >>>
    >>> even with no sound.
    >>
    > Well, it is a regression caused by your fix. Without it (and not reverting
    > the already applied ignore patch), runtime is properly suspended. Don't know
    > why yet.

    I guess it is because of the pm_runtime_put_sync() in the
    omap2_mcbsp_set_clks_src() around the fclk re-parenting.
    That is a bit dubious thing for sure. We need to disable the device to
    be able to re-parent the fclk but if we disable the device it is going
    to be powered down, right? I think we have appropriate context handling,
    so it might work, but it is certainly not a rock solid code... If you
    have a stream running already, you don't really want to kill the McBSP.

    The problem is that this mux is outside of the McBSP IP, so we need a
    system level (iow, clk API) way to change it runtime.

    What is the machine driver where this happens? If you set the sysclk in
    hw_params of the machine driver, it will be OK, but if you do that in
    probe time then it is likely going to fail as you experienced

    --
    Péter

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