Re: [PATCH v4 5/5] clk: rockchip: rk3588: add GATE_GRF clocks for I2S MCLK output to IO

[Daniele Briguglio]

Hi Heiko,

> can you check if adding CLK_IGNORE_UNUSED changes the situation for you?
> What I assume is happening is that when the clocks were not declared they were
> just left running, while now the kernel turns off unused (but defined) clocks.

That lines up with what I see. The gates are set-to-disable and reset to
open, so before the series the bit just kept whatever the boot firmware
left it at.

Diederik, the cleanest way to confirm is to read SOC_CON6 before Linux
touches it, e.g. md.l 0xfd58c318 at the U-Boot prompt (bit 0 is I2S0). If
it comes up clear there, the gate is open, and if audio then breaks once
the kernel is up, that points at clk_disable_unused turning it off because
nothing references it.

If that turns out to be the case, CLK_IGNORE_UNUSED on the gates is a
reasonable way to stop the kernel from closing a gate the firmware already
left open, for boards that would rather not switch their DTS to _TO_IO.
Where a board does reference _TO_IO the consumer holds it open anyway, so
that path is unaffected either way.

Best regards,
Daniele