Boris Brezillon [off-list ref] writes:

Some peripheral clocks, like the VEC (Video EnCoder) clock need to be set
to a precise rate (in our case 108MHz). With the current implementation,
where peripheral clocks are not allowed to forward rate change requests
to their parents, it is impossible to match this requirement unless the
bootloader has configured things correctly, or a specific rate has been
assigned through the DT (with the assigned-clk-rates property).

Add a new field to struct bcm2835_clock_data to specify which parent
clocks accept rate change propagation, and support set rate propagation
in bcm2835_clock_determine_rate().

Signed-off-by: Boris Brezillon <redacted>

A possible simplification would be to limit VEC to only PLLH_AUX, since
that was how the HW designers intended it to be used.  Then you could
just have SET_RATE_PARENT flag, rather than the bitfield.

Still, this seems to be correct and fixes the bug.  Both patches are:

Reviewed-by: Eric Anholt <redacted>
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