Re: [PATCH v4 0/5] clk: rockchip: rk3588: add I2S MCLK output gate clocks

Re: [PATCH v4 0/5] clk: rockchip: rk3588: add I2S MCLK output gate clocks

[Heiko Stuebner]

On Sun, 19 Apr 2026 13:43:05 +0200, Daniele Briguglio wrote:
> On RK3588, the four I2S master clock (MCLK) outputs to external IO
> pins are gated by bits in SYS_GRF SOC_CON6 (offset 0x0318). These
> are set-to-disable gates with hiword mask semantics.
> 
> The TRM documents the reset value of these bits as 0 (gate open),
> but in practice the Rockchip firmware (BL31) may set them during
> early boot, preventing the MCLK signal from reaching external audio
> codecs. The kernel should manage these gates explicitly so that
> audio functionality does not depend on bootloader register state.
> 
> [...]

Applied, thanks!

[1/5] dt-bindings: clock: rockchip,rk3588-cru: add I2S MCLK output to IO clock IDs
      commit: 56c2ca0ae7cb9254c4c2b82baa0afe29feaa274e
[2/5] clk: rockchip: allow grf_type_sys lookup in aux_grf_table
      commit: 28820fc7983b9c8e160c0095067a570bdfcae1f0
[3/5] clk: rockchip: add helper to register auxiliary GRFs
      commit: 32d1d88c4165d0da31d3bfda912e80e8110d6fc1
[4/5] soc: rockchip: rk3588: add SYS_GRF SOC_CON6 register offset
      commit: 06c990bffdbea7cf655e728f4423ecd13fb030f6
[5/5] clk: rockchip: rk3588: add GATE_GRF clocks for I2S MCLK output to IO
      commit: 02b9b0bb626989b947d82bbe4e050f0254e2046d

Best regards,
-- 
Heiko Stuebner <heiko@sntech.de>

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

[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.

Cheers,
  Diederik

> [1] https://lore.kernel.org/r/20250305-rk3576-sai-v1-2-64e6cf863e9a@collabora.com/
>
> Tested-by: Ricardo Pardini <ricardo@pardini.net>
> Signed-off-by: Daniele Briguglio <hello@superkali.me>
> ---
>  drivers/clk/rockchip/clk-rk3588.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/clk/rockchip/clk-rk3588.c b/drivers/clk/rockchip/clk-rk3588.c
> index 1694223f4f84..2ba9976654cf 100644
> --- a/drivers/clk/rockchip/clk-rk3588.c
> +++ b/drivers/clk/rockchip/clk-rk3588.c
> @@ -5,11 +5,13 @@
>   */
>  
>  #include <linux/clk-provider.h>
> +#include <linux/mfd/syscon.h>
>  #include <linux/of.h>
>  #include <linux/of_address.h>
>  #include <linux/platform_device.h>
>  #include <linux/syscore_ops.h>
>  #include <dt-bindings/clock/rockchip,rk3588-cru.h>
> +#include <soc/rockchip/rk3588_grf.h>
>  #include "clk.h"
>  
>  #define RK3588_GRF_SOC_STATUS0		0x600
> @@ -892,6 +894,8 @@ static struct rockchip_clk_branch rk3588_early_clk_branches[] __initdata = {
>  			RK3588_CLKGATE_CON(8), 0, GFLAGS),
>  	MUX(I2S2_2CH_MCLKOUT, "i2s2_2ch_mclkout", i2s2_2ch_mclkout_p, CLK_SET_RATE_PARENT,
>  			RK3588_CLKSEL_CON(30), 2, 1, MFLAGS),
> +	GATE_GRF(I2S2_2CH_MCLKOUT_TO_IO, "i2s2_2ch_mclkout_to_io", "i2s2_2ch_mclkout",
> +			0, RK3588_SYSGRF_SOC_CON6, 2, GFLAGS, grf_type_sys),
>  
>  	COMPOSITE(CLK_I2S3_2CH_SRC, "clk_i2s3_2ch_src", gpll_aupll_p, 0,
>  			RK3588_CLKSEL_CON(30), 8, 1, MFLAGS, 3, 5, DFLAGS,
> @@ -907,6 +911,8 @@ static struct rockchip_clk_branch rk3588_early_clk_branches[] __initdata = {
>  			RK3588_CLKGATE_CON(8), 4, GFLAGS),
>  	MUX(I2S3_2CH_MCLKOUT, "i2s3_2ch_mclkout", i2s3_2ch_mclkout_p, CLK_SET_RATE_PARENT,
>  			RK3588_CLKSEL_CON(32), 2, 1, MFLAGS),
> +	GATE_GRF(I2S3_2CH_MCLKOUT_TO_IO, "i2s3_2ch_mclkout_to_io", "i2s3_2ch_mclkout",
> +			0, RK3588_SYSGRF_SOC_CON6, 7, GFLAGS, grf_type_sys),
>  	GATE(PCLK_ACDCDIG, "pclk_acdcdig", "pclk_audio_root", 0,
>  			RK3588_CLKGATE_CON(7), 11, GFLAGS),
>  	GATE(HCLK_I2S0_8CH, "hclk_i2s0_8ch", "hclk_audio_root", 0,
> @@ -935,6 +941,8 @@ static struct rockchip_clk_branch rk3588_early_clk_branches[] __initdata = {
>  			RK3588_CLKGATE_CON(7), 10, GFLAGS),
>  	MUX(I2S0_8CH_MCLKOUT, "i2s0_8ch_mclkout", i2s0_8ch_mclkout_p, CLK_SET_RATE_PARENT,
>  			RK3588_CLKSEL_CON(28), 2, 2, MFLAGS),
> +	GATE_GRF(I2S0_8CH_MCLKOUT_TO_IO, "i2s0_8ch_mclkout_to_io", "i2s0_8ch_mclkout",
> +			0, RK3588_SYSGRF_SOC_CON6, 0, GFLAGS, grf_type_sys),
>  
>  	GATE(HCLK_PDM1, "hclk_pdm1", "hclk_audio_root", 0,
>  			RK3588_CLKGATE_CON(9), 6, GFLAGS),
> @@ -2220,6 +2228,8 @@ static struct rockchip_clk_branch rk3588_early_clk_branches[] __initdata = {
>  			RK3588_PMU_CLKGATE_CON(2), 13, GFLAGS),
>  	MUX(I2S1_8CH_MCLKOUT, "i2s1_8ch_mclkout", i2s1_8ch_mclkout_p, CLK_SET_RATE_PARENT,
>  			RK3588_PMU_CLKSEL_CON(9), 2, 2, MFLAGS),
> +	GATE_GRF(I2S1_8CH_MCLKOUT_TO_IO, "i2s1_8ch_mclkout_to_io", "i2s1_8ch_mclkout",
> +			0, RK3588_SYSGRF_SOC_CON6, 1, GFLAGS, grf_type_sys),
>  	GATE(PCLK_PMU1, "pclk_pmu1", "pclk_pmu0_root", CLK_IS_CRITICAL,
>  			RK3588_PMU_CLKGATE_CON(1), 0, GFLAGS),
>  	GATE(CLK_DDR_FAIL_SAFE, "clk_ddr_fail_safe", "clk_pmu0", CLK_IGNORE_UNUSED,
> @@ -2439,6 +2449,7 @@ static struct rockchip_clk_branch rk3588_clk_branches[] = {
>  static void __init rk3588_clk_early_init(struct device_node *np)
>  {
>  	struct rockchip_clk_provider *ctx;
> +	struct regmap *sys_grf;
>  	unsigned long clk_nr_clks, max_clk_id1, max_clk_id2;
>  	void __iomem *reg_base;
>  
> @@ -2479,6 +2490,11 @@ static void __init rk3588_clk_early_init(struct device_node *np)
>  			&rk3588_cpub1clk_data, rk3588_cpub1clk_rates,
>  			ARRAY_SIZE(rk3588_cpub1clk_rates));
>  
> +	/* Register SYS_GRF for I2S MCLK output to IO gate clocks */
> +	sys_grf = syscon_regmap_lookup_by_compatible("rockchip,rk3588-sys-grf");
> +	if (!IS_ERR(sys_grf))
> +		rockchip_clk_add_grf(ctx, sys_grf, grf_type_sys);
> +
>  	rockchip_clk_register_branches(ctx, rk3588_early_clk_branches,
>  				       ARRAY_SIZE(rk3588_early_clk_branches));
>  

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

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

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

[Diederik de Haas]

On Tue Jun 23, 2026 at 2:33 PM CEST, Daniele Briguglio wrote:
>> 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.

NanoPC-T6 LTS
U-Boot: 2026.04-00003-g723f0da896bc

The 0003 comes from me adding patches for NanoPC-T6 Plus support, but
otherwise it's plain upstream U-Boot.

=> md.l 0xfd58c318
fd58c318: 00000600 00000a00 00000000 00000000  ................
fd58c328: 00000300 00092820 0fd58c338: 00000000 00000000 00000000 00000000  ................
fd58c348: 00000000 00000000 00000000 00000000  ................c358: 00000000 00000000 00000000 00000000  ................
fd58c368: 00000000 00000000 00000008: 00000000 00000000 00001000 00000240  ............@...
fd58c388: 0000003f 0000fefe 00000000 000000000 00000000 00000000 00000000  ................
fd58c3a8: 00000000 00000000 00000000 00000000 00000000 00000000 00000000  ................
fd58c3c8: 00000000 00000000 00000000 000000000 00000000 00000000 00000000  ................
fd58c3e8: 00000000 00000000 00000000 00000000  .0000000 00000000 00000000  ................
fd58c408: 00000000 00000000 00000000 00000000  ....

I'll let interpreting it up to you.

> 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.

I'm not so sure I agree that CLK_IGNORE_UNUSED is reasonable, but I'll leave
judgement up to others. I'll do the test regardless, though.

Cheers,
  Diederik

> Where a board does reference _TO_IO the consumer holds it open anyway, so
> that path is unaffected either way.
>
> Best regards,
> Daniele

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

[Diederik de Haas]

On Tue Jun 23, 2026 at 3:05 PM CEST, Diederik de Haas wrote:
> On Tue Jun 23, 2026 at 2:33 PM CEST, Daniele Briguglio wrote:
>> 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.
>
> I'm not so sure I agree that CLK_IGNORE_UNUSED is reasonable, but I'll leave
> judgement up to others. I'll do the test regardless, though.

Ah, just learned those should be added to your patch, in which case my
objection goes away.

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

[Daniele Briguglio]

Hi Diederik,

> md.l 0xfd58c318
> fd58c318: 00000600

Thanks. Bit 0 is clear there, so the I2S0 gate is open at the U-Boot
prompt, after BL31 and before Linux. That matches the symptom: the
firmware on your T6 leaves it open, and the kernel closes it once nothing
references it.

Given that, I think Heiko's suggestion makes sense here. Marking the four
gates CLK_IGNORE_UNUSED keeps the kernel from disabling what the firmware
already left open, and boards that reference _TO_IO still drive it through
the consumer.

Could you test that change if you get a chance? Just set the flag on the
I2S0/1/2/3 _TO_IO gates in clk-rk3588.c and check your analog audio comes
back. The series is already merged, so I'll send the fix as a separate
follow-up patch, this evening if Heiko is fine with the approach.

Best regards,
Daniele

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

[Diederik de Haas]

Hi Daniele,

On Tue Jun 23, 2026 at 3:23 PM CEST, Daniele Briguglio wrote:
>> md.l 0xfd58c318
>> fd58c318: 00000600
>
> Thanks. Bit 0 is clear there, so the I2S0 gate is open at the U-Boot
> prompt, after BL31 and before Linux. That matches the symptom: the
> firmware on your T6 leaves it open, and the kernel closes it once nothing
> references it.
>
> Given that, I think Heiko's suggestion makes sense here. Marking the four
> gates CLK_IGNORE_UNUSED keeps the kernel from disabling what the firmware
> already left open, and boards that reference _TO_IO still drive it through
> the consumer.

My suspicion that more RK3588 based boards would be broken is because NONE use
I2S0_8CH_MCLKOUT_TO_IO; they all use I2S0_8CH_MCLKOUT.
(And the testing was only done on not (yet?) upstreamed boards)

> Could you test that change if you get a chance? Just set the flag on the
> I2S0/1/2/3 _TO_IO gates in clk-rk3588.c and check your analog audio comes
> back. The series is already merged, so I'll send the fix as a separate
> follow-up patch, this evening if Heiko is fine with the approach.

I'm going to build a new kernel where I did ``s/0/CLK_IGNORE_UNUSED/`` 4 times
and I adjusted my NanoPC-T6 Plus board dts to use I2S0_8CH_MCLKOUT_TO_IO, while
I keep the LTS board dts to I2S0_8CH_MCLKOUT.
So IIUC that means I'd be testing both variants.

Cheers,
  Diederik

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

[Daniele Briguglio]

Hi Diederik,

> My suspicion that more RK3588 based boards would be broken is because NONE use
> I2S0_8CH_MCLKOUT_TO_IO; they all use I2S0_8CH_MCLKOUT.

These bits reset to open (SYS_GRF_SOC_CON6 = 0x4600, i2sN_mclk_ioe_ clear,
1'b0 = "Output enable"), so a board doesn't need to reference the gate to
get MCLK. They're RW, so firmware can go either way, but your 0x600 has
them clear, which is why audio works today.

The series made the gate a managed clock, so with no consumer
clk_disable_unused disables it at boot. CLK_IGNORE_UNUSED leaves an
already-open gate alone, so nothing changes for those boards. Only the ones
that come up disabled, like the YY3588 and Ricardo's R58X-Pro, need _TO_IO
for the kernel to turn it back on.

> So IIUC that means I'd be testing both variants.

Right, that covers both: the mux path and the consumer path. Looking
forward to the results.

Best regards,
Daniele