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    SubjectRe: [PATCH v2 2/2] clk: clarify that clk_set_rate() does updates from top to bottom
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    Quoting Martin Blumenstingl (2019-12-26 11:12:24)
    > clk_set_rate() currently starts updating the rate for a clock at the
    > top-most affected clock and then walks down the tree to update the
    > bottom-most affected clock last.
    > This behavior is important for protected clocks where we can switch
    > between multiple parents to achieve the same output.
    >
    > An example for this is the mali clock tree on Amlogic SoCs:
    > mali_0_mux (must not change when enabled)
    > mali_0_div (must not change when enabled)
    > mali_0 (gate)
    > mali_1_mux (must not change when enabled)
    > mali_1_div (must not change when enabled)
    > mali_1 (gate)
    > The final output can either use mali_0_gate or mali_1. To change the
    > final output we must switch to the "inactive" tree. Assuming mali_0 is
    > active, then we need to prepare mali_1 with the new desired rate and
    > finally switch the output to the mali_1 tree. This process will then
    > protect the mali_1 tree and at the same time unprotect the mali_0 tree.
    > The next call to clk_set_rate() will then switch from the mali_1 tree
    > back to mali_0.
    >
    > Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
    > ---

    Acked-by: Stephen Boyd <sboyd@kernel.org>

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