[PATCH v8 1/2] arm64: dts: imx8mp: Add SAI, SDMA, AudioMIX

[Marek Vasut]

On 8/30/23 04:44, Adam Ford wrote:

Hi,

> I have a question about the clocking for eASRC and PDM.
> 
>> +
>> +                       audio_blk_ctrl: clock-controller at 30e20000 {
>> +                               compatible = "fsl,imx8mp-audio-blk-ctrl";
>> +                               reg = <0x30e20000 0x10000>;
>> +                               #clock-cells = <1>;
>> +                               clocks = <&clk IMX8MP_CLK_AUDIO_ROOT>,
>> +                                        <&clk IMX8MP_CLK_SAI1>,
>> +                                        <&clk IMX8MP_CLK_SAI2>,
>> +                                        <&clk IMX8MP_CLK_SAI3>,
>> +                                        <&clk IMX8MP_CLK_SAI5>,
>> +                                        <&clk IMX8MP_CLK_SAI6>,
>> +                                        <&clk IMX8MP_CLK_SAI7>;
>> +                               clock-names = "ahb",
>> +                                             "sai1", "sai2", "sai3",
>> +                                             "sai5", "sai6", "sai7";
>> +                               power-domains = <&pgc_audio>;
>> +                       };
>> +               };
>> +
> 
> I am trying to plumb in the micfil driver with a PDM microphone on a
> Plus.  I have SAI3 and SAI5 audio working, but if I try to use the
> micfil, the PDM clock doesn't get turned on, and the micfil doesn't
> appear to see anything coming in.  I was curious why the
> audio_blk_ctrl has clock entries for IMX8MP_CLK_SAIx, but there isn't
> one for the PDM nor the ASRC clocks.

I only ever needed SAI, so that was what was tested on the EVK .

> I added the MICFIL noted to the
> 8mp in a previous patch [1], and I am trying to customize the MICFIL
> node as follows:
> 
> &micfil {
> #sound-dai-cells = <0>;
> pinctrl-names = "default";
> pinctrl-0 = <&pinctrl_pdm>;
> assigned-clocks = <&clk IMX8MP_CLK_PDM>;
> assigned-clock-parents = <&clk IMX8MP_AUDIO_PLL1_OUT>;
> assigned-clock-rates = <196608000>;
> status = "okay";
> };
> 
> I also noticed in the down-stream kernel, the pdm_ipg_clk and
> pdm_root_clk are shared gates with separate parents.
> 
> The PDM tree of the down-stream kernel looks like this:
>   audio_pll1_ref_sel                0        0        0    24000000
>       0     0  50000         Y
>         audio_pll1                     0        0        0   393216000
>          0     0  50000         Y
>            audio_pll1_bypass           0        0        0   393216000
>          0     0  50000         Y
>               audio_pll1_out           0        0        0   393216000
>          0     0  50000         N
>                  pdm                   0        0        0   196608000
>          0     0  50000         N
>                     pdm_root           0        0        0   196608000
>          0     0  50000         N
>                        pdm_sel         0        0        0   196608000
>          0     0  50000         Y
>                           pdm_root_clk       0        0        0
> 196608000          0     0  50000         N
> 
> The PDM tree of the mainline looks like this:
> 
>     audio_pll1_ref_sel                0        0        0    24000000
>         0     0  50000         Y
>         audio_pll1                     0        0        0   393216000
>          0     0  50000         Y
>            audio_pll1_bypass           0        0        0   393216000
>          0     0  50000         Y
>               audio_pll1_out           0        0        0   393216000
>          0     0  50000         N
>                  pdm                   0        0        0   196608000
>          0     0  50000         N
>                     pdm_root           0        0        0   196608000
>          0     0  50000         N
>                        pdm_sel         0        0        0   196608000
>          0     0  50000         Y
> 
> It seems like the "pdm_root_clk" generated by the shared audo-blk
> down-sream driver is missing from the mainline.  I looked up the clock
> I referenced when I attempted to enable the miffil, but
> 'IMX8MP_CLK_AUDIOMIX_PDM_ROOT doesn't appear to be configured in
> either clk-imx8mp.c or clk-imx8mp-audiomix.c.  Maybe it's obscured by
> the macros, but it seems like the pdm_sel should somehow have an
> additional variable for the shared clock and an additional clock like
> pdm_root_clk assigned with it.
> 
> I have similar configurations for Mini and Nano, and both of them are
> able to record audio, so I think there might be a clock issue
> somewhere related to the audiomix driver, and not a misconfiguration
> of the sound-card or the micfil itself.

Shouldn't the micfil be somehow a consumer of the pdm_sel clock , and 
enable those clock in the driver ?