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

[Heiko Stübner]

Hi Diederick,

Am Dienstag, 23. Juni 2026, 13:10:49 Mitteleuropäische Sommerzeit schrieb Diederik de Haas:
> [Resending it against v4 which wasn't present in my INBOX, but was the
> version accepted and used in my kernel]
> 
> On Tue Jun 23, 2026 at 1:08 PM CEST, Daniele Briguglio wrote:
> > The I2S MCLK outputs on RK3588 are gated by bits in the SYS_GRF
> > register SOC_CON6 (offset 0x318). These gates control whether the
> > internal CRU MCLK signals reach the external IO pins connected to
> > audio codecs.
> >
> > The kernel should explicitly manage these gates so that audio
> > functionality does not depend on bootloader register state. This is
> > analogous to what was done for RK3576 SAI MCLK outputs [1].
> >
> > Register the SYS_GRF as an auxiliary GRF with grf_type_sys using
> > rockchip_clk_add_grf(), and add GATE_GRF entries for all four I2S
> > MCLK output gates:
> >
> >   - I2S0_8CH_MCLKOUT_TO_IO (bit 0)
> >   - I2S1_8CH_MCLKOUT_TO_IO (bit 1)
> >   - I2S2_2CH_MCLKOUT_TO_IO (bit 2)
> >   - I2S3_2CH_MCLKOUT_TO_IO (bit 7)
> >
> > Board DTS files that need MCLK on an IO pin can reference these
> > clocks, e.g.:
> >
> >     clocks = <&cru I2S0_8CH_MCLKOUT_TO_IO>;
> >
> > Tested on the Youyeetoo YY3588 (RK3588) with an ES8388 codec on I2S0.
> 
> Doesn't this break audio on a lot of RK3588 based boards?
> I have a kernel with this patch set and since then analog audio on my NanoPC-T6
> LTS and my WIP NanoPC-T6 Plus stopped working.
> Until I did s/I2S0_8CH_MCLKOUT/I2S0_8CH_MCLKOUT_TO_IO/ in my dts[i] files.
> 
> And I wouldn't be surprised if the same thing applies to other RK3588 based
> boards? The same dtb file with a 7.1 kernel, without this patch set, works.

can you check if adding CLK_IGNORE_UNUSED [0] 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 of unused (but defined) clocks.


[0] example in
https://elixir.bootlin.com/linux/v7.1.1/source/drivers/clk/rockchip/clk-rk3588.c#L865