In the event that the bootloader has configured the Trion PLL as source
for the display clocks, e.g. for the continuous splashscreen, then there
will also be RCGs that are clocked by this instance.

Reconfiguring, and in particular disabling the output of, the PLL will
cause issues for these downstream RCGs and has been shown to prevent
them from being re-parented.

Follow downstream and skip configuration if it's determined that the PLL
is already running.

Fixes: 59128c20 ("clk: qcom: clk-alpha-pll: Add support for controlling Lucid PLLs")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20211123162508.153711-1-bjorn.andersson@linaro.orgSigned-off-by: Stephen Boyd <sboyd@kernel.org>