On 8/31/23 06:32, Adam Ford wrote:
On Wed, Aug 30, 2023 at 3:50 PM Marek Vasut <marex@xxxxxxx> wrote:
On 8/30/23 21:59, Adam Ford wrote:
On Wed, Aug 30, 2023 at 2:10 PM Marek Vasut <marex@xxxxxxx> wrote:
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@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 .
That makes sense.
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 ?
Micfil references IMX8MP_CLK_AUDIOMIX_PDM_IPG, and
IMX8MP_CLK_AUDIOMIX_PDM_ROOT. I am not convinced the
IMX8MP_CLK_AUDIOMIX_PDM_ROOT exists beyond a #define in an include
directory. I tried making it use pdm_sel, but it threw an error. I
am not near my system, so I'm sorry I don't have more details.
In the downstream kernel IMX8MP_CLK_AUDIOMIX_PDM_ROOT was a child of
pdm_sel, but I am not certain as to what the difference between them
was since they appeared to be shared.
The pdm_sel is definitely a mux . Is there a follow-up gate after the mux ?
Not that I could see. I think I was just overthinking it. I saw the
IMX8MP_CLK_AUDIOMIX_PDM_ROOT in mx8mp-clock.h which matched the
reference in the downstream kernel, so I was expecting that to be the
same clock name. When it didn't work, I thought I was missing
something because I only saw the pdm_sel mux and no direct reason or
reference to IMX8MP_CLK_AUDIOMIX_PDM_ROOT. I have it working now.
Sorry for the noise. I'll get my series cleaned up and push another
revision to add micfil node to the 8mp, and I'll probably remove the
IMX8MP_CLK_AUDIOMIX_PDM_ROOT imx8mp-clock.h so it doesn't throw
someone else off.
No worries, good thing you found it. Thanks for investigating it.
