[REGRESSION] Re: [PATCH v1] ASoC: rockchip: i2s_tdm: Re-add the set_sysclk callback

[Luca Ceresoli]

Hello Detlev,

On Tue Feb 10, 2026 at 10:54 AM CET, Luca Ceresoli wrote:
> Hello Detlev,
>
> On Fri Jan 17, 2025 at 5:31 PM CET, Detlev Casanova wrote:
>> In commit
>> 9e2ab4b18ebd ("ASoC: rockchip: i2s-tdm: Fix inaccurate sampling rates"),
>> the set_sysclk callback was removed as considered unused as the mclk rate
>> can be set in the hw_params callback.
>> The difference between hw_params and set_sysclk is that the former is
>> called with the audio sampling rate set in the params (e.g.: 48000 Hz)
>> while the latter is called with a clock rate already computed with
>>   sampling_rate * mclk-fs (e.g.: 48000 * 256)
>>
>> For HDMI audio using the Rockchip I2S TDM driver, the mclk-fs value must
>> be set to 128 instead of the default 256, and that value is set in the
>> device tree at the machine driver level (like a simple-audio-card
>> compatible node).
>> Therefore, the i2s_tdm driver has no idea that another mclk-fs value can
>> be configured and simply computes the mclk rate in the hw_params callback
>> with DEFAULT_MCLK_FS * params_rate(params), which is wrong for HDMI
>> audio.
>>
>> Re-add the set_sysclk callback so that the mclk rate is computed by the
>> machine driver which has the correct mclk-fs value set in its device tree
>> node.
>
> I'm afraid I just found this commit breaks audio capture on the RK3308.
>
> Using 'arecord -Vmono -d 2 -c 8 -f S16_LE -r 96000 /dev/null' I get:
>
>   rockchip-i2s-tdm ff320000.i2s: ASoC error (-22): at snd_soc_dai_hw_params() on ff320000.i2s
>    ff320000.i2s-rk3308-hifi: ASoC error (-22): at __soc_pcm_hw_params() on ff320000.i2s-rk3308-hifi
>
> Tested on:
>
>  * Radxa Rock Pi S
>  * Upstream kernel
>  * arm64 defconfig
>
> Tested kernel versions:
>
>  * v6.12 works
>  * 5323186e2e8d (this commit) fails
>  * 5323186e2e8d^ works
>  * 21cfbeae7d7c (same patch on stable/linux-6.12.y) fails
>  * 21cfbeae7d7c^ works
>  * v6.19 fails
>  * v6.19 + 'git revert 5323186e2e8d' works
>
> I don't have more information at the moment.

Let me add some more info to my previous report.

The function failing is clk_set_rate() in rockchip_i2s_tdm_hw_params().

I added some logging to rockchip_i2s_tdm_hw_params() and here's the output:

  On v6.19-11566-g254edc893f3a (current Linux master)

  At boot:
    [    3.324622] rockchip-i2s-tdm ff320000.i2s: The target mclk_tx freq is: 50176000
    [    3.324720] rockchip-i2s-tdm ff320000.i2s: using zero-initialized flat cache, this may cause unexpected behavior
  When launching arecord:
    [   18.429389] rockchip_i2s_tdm_hw_params:653 i2s_tdm->is_master_mode = 1
    [   18.430154] rockchip_i2s_tdm_hw_params:654 i2s_tdm->mclk_tx clk_i2s2_8ch_tx
    [   18.430815] rockchip_i2s_tdm_hw_params:655 i2s_tdm->mclk_rx clk_i2s2_8ch_rx
    [   18.431465] rockchip_i2s_tdm_hw_params:656 i2s_tdm->mclk_tx_freq 50176000
    [   18.432097] rockchip_i2s_tdm_hw_params:657 i2s_tdm->mclk_rx_freq 0
    [   18.432677] rockchip_i2s_tdm_hw_params:658 i2s_tdm->clk_trcm 0
    [   18.433230] rockchip_i2s_tdm_hw_params:659 substream->stream 1
    [   18.433858] rockchip_i2s_tdm_hw_params:678 mclk clk_i2s2_8ch_rx
    [   18.434423] rockchip_i2s_tdm_hw_params:679 mclk_rate 0
    [   18.434977] rockchip_i2s_tdm_hw_params:682 clk_set_rate(clk_i2s2_8ch_rx, 0) returned -22
    [   18.435743] rockchip-i2s-tdm ff320000.i2s: ASoC error (-22): at snd_soc_dai_hw_params() on ff320000.i2s
    [   18.436699]  ff320000.i2s-rk3308-hifi: ASoC error (-22): at __soc_pcm_hw_params() on ff320000.i2s-rk3308-hifi

  On v6.19-11566-g254edc893f3a + 'git revert 5323186e2e8d'

  At boot:
    [    3.283853] rockchip-i2s-tdm ff320000.i2s: using zero-initialized flat cache, this may cause unexpected behavior
  When launching arecord:
    [   11.952290] rockchip_i2s_tdm_hw_params:631 i2s_tdm->is_master_mode = 1
    [   11.952955] rockchip_i2s_tdm_hw_params:632 i2s_tdm->mclk_tx clk_i2s2_8ch_tx
    [   11.953615] rockchip_i2s_tdm_hw_params:633 i2s_tdm->mclk_rx clk_i2s2_8ch_rx
    [   11.954355] rockchip_i2s_tdm_hw_params:636 i2s_tdm->clk_trcm 0
    [   11.954917] rockchip_i2s_tdm_hw_params:637 substream->stream 1
    [   11.955477] rockchip_i2s_tdm_hw_params:652 mclk clk_i2s2_8ch_rx
    [   11.956048] rockchip_i2s_tdm_hw_params:653 params_rate(params) 96000
    [   11.956769] rockchip_i2s_tdm_hw_params:656 clk_set_rate(clk_i2s2_8ch_rx, 24576000) returned 0

I cannot point to the right fix but the value 0 in i2s_tdm->mclk_rx_freq
appears as a good clue, perhaps it has never been set.

I hope this helps.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com