[Query] Common Clock Framework: How to handle clks enabled by default

Viresh Kumar viresh.kumar at st.com
Tue Apr 17 02:21:45 EDT 2012


Hi,

How are we handling clocks which are enabled by bootloaders and are
required to be enabled, like, pll, cpu, ahb?

Following is example clk hierarchy:
osc(root)->pll->cpu->ahb->dma

Issue1: Now, when we do clk_enable() for dma, all these already enabled clocks
are re-enabled.
Issue2: On clk_disable() all are disabled and system hangs :(

There is one option CLK_IGNORE_UNUSED, which is used only for disabling
unused clocks. So that is not helpful here.

One way i could think of is not to give clk_gate support for these clocks,
so that they can never be disabled. Is this the preferred way?

I can't guarantee, but these clocks might be required to be disabled
for standby/sleep cases.

-- 
viresh



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