topic Re: How to enable SAI MCLK on iMX8MP? in i.MX Processors

How to enable SAI MCLK on iMX8MP?

ensc — Tue, 26 Jul 2022 16:35:17 GMT

What is required to output a clock e.g. on the `SAI2_MCLK` pin?

With iMX8MM, the clock started immediately after iomux have been configured. E.g. in barebox bootloader I see the signal after

mw 0x303301c8 0

But on iMX8MP the signal stays static

mw 0x303a00d8 32 ## power up audio block mw 0x303301b4 0 ## ALT0_AUDIOMIX_SAI2_MCLK

and can be toggled by changing pull up/down settings

mw 0x30330414 0x140 ## signal becomes high mw 0x30330414 0x100 ## signal becomes low

Clocks are enabled, audio_blk_ctrl controller is having power-on settings and I enabled MOE in SAI MCTL:

md 0x30384650 30384650: 00000003 00000003 00000003 00000003 ................ :/ md 0x30e20000+8 30e20000: ff777777 0000003f www.?... :/ md 0x30e20300+0x20 30e20300: 00000000 00000000 00000000 00000000 ................ 30e20310: 00000000 00000000 00000000 00000000 ................ :/ md 0x30c20100 30c20100: 80000000 00000000 xxxxxxxx xxxxxxxx ................

What has to be configured else to output the MCLK signal? I require it for using an SGTL5000 which needs MCLK for its i2c communication.

Re: How to enable SAI MCLK on iMX8MP?

Dhruvit — Thu, 18 Aug 2022 11:33:47 GMT

Hi @ensc,

I think there is no dependency of MCLK on I2C to work.

Could you please confirm at your end if there is something that you are missing related to any pins/GPIOs or SGTL5000?

Best Regards,
Dhruvit.

Re: How to enable SAI MCLK on iMX8MP?

ensc — Thu, 18 Aug 2022 13:30:29 GMT

I think there is no dependency of MCLK on I2C to work.

MCLK is required; see Table 7 "Dynamic Electrical Characteristics", note 1

The SGTL5000 has an internal reset that is deasserted 8 SYS_MCLK cycles after all power rails have been brought up. After this time, communication can start.

and figure 4 "Power Up Timing"

But this question is about the iMX8MP; I want to know how to generate SAI MCLK there.

Re: How to enable SAI MCLK on iMX8MP?

Dhruvit — Thu, 18 Aug 2022 13:35:39 GMT

Hi @ensc,

Could you please try playing/recording something first to make SAI work?

For example, with default i.MX8MP evk, when I use the wm8960 for playback, SAI3 will be used, then I can read the register like,

ot@imx8mpevk:~# /unit_tests/memtool 30e20000 1 E Reading 0x1 count starting at address 0x30E20000 0x30E20000: 04000300

Best Regards,
Dhruvit.

Re: How to enable SAI MCLK on iMX8MP?

ensc — Thu, 18 Aug 2022 13:49:37 GMT

Could you please try playing/recording something first to make SAI work?

The problem is, that I can not play or record anything because I can not initialize the SGTL5000 due to the missing SAI_MCLK.

With iMX8MM on a similar hardware, this clock was easy to generate just by setting iomux. This does not work anymore with iMX8MP.

What have I to do for generating SAI_MCLK?

For example, with default i.MX8MP evk, when I use the wm8960 for playback

I do not know the wm8960; perhaps its I2C works without the global mclk.

Re: How to enable SAI MCLK on iMX8MP?

Dhruvit — Wed, 31 Aug 2022 07:10:42 GMT

Hi @ensc,

I have sent the additional details over email.

Thank you.

Best Regards,
Dhruvit.

Re: How to enable SAI MCLK on iMX8MP?

VoVan — Mon, 21 Nov 2022 10:30:16 GMT

Can you see a solution to this problem? I have the same situation, the sgtl5000 works fine on the imx8mm board, since a normal clock is generated (MCLK - SAI3), but on the imx8mp board the clock does not work, as a result, there is no i2c device.

Re: How to enable SAI MCLK on iMX8MP?

ensc — Mon, 21 Nov 2022 11:12:41 GMT

`FSL_SAI_MCTL_MCLK_EN` + `FSL_SAI_CSR_TERE` must be enabled to generate the clock.

I solved it by making SAI a clock provider and enable MCLK in sgtl5000 when needed.

- https://git.data-modul.com/i.mx8mm-std-mirror/components/kernel/-/commit/6dc48366bd8ce5778183ac0d5ed967e346334246

- https://git.data-modul.com/i.mx8mm-std-mirror/components/kernel/-/commit/9521345a094391fcab628aedcf7f6ace58f49bd0

- https://git.data-modul.com/i.mx8mm-std-mirror/components/kernel/-/commit/dae9f931fb1472a410383cd257048b2b9cf049b3

- https://git.data-modul.com/i.mx8mm-std-mirror/components/kernel/-/commit/49e16c26682b54bff23ffce4ec4446c88a3d3a70

- https://git.data-modul.com/i.mx8mm-std-mirror/meta-dmo-imx8/-/blob/ac485fc6d075520aa0f27c6a54865a2b0664b30f/recipes-bsp/devicetree/dtree/imx8mp-dmo-sbc__base.dtsi#L877

It is racy like hell but works for now. Future hardware will probably replace the SGTL5000

Re: How to enable SAI MCLK on iMX8MP?

VoVan — Mon, 21 Nov 2022 11:59:35 GMT

Thanks, i'll try add this patches

Re: How to enable SAI MCLK on iMX8MP?

edwardtyrrell — Tue, 22 Nov 2022 10:57:21 GMT

Hi @ensc

Have you resolved your issues?

Re: How to enable SAI MCLK on iMX8MP?

Eddy1 — Tue, 12 Mar 2024 01:40:27 GMT

Hi:

Can your sgtl5000 work properly? Can you provide your device tree configuration? Currently, I followed your patch, but there is still no mclk output.

Re: How to enable SAI MCLK on iMX8MP?

siegfried_buerger — Tue, 22 Jul 2025 12:08:35 GMT

I also have a problem to enable a clock output at SAI3_MCLK. In my case I need the clock for a first board hardware test before Linux will be installed. My situation is that any access to the AUDIO_BLK_CTRL bock for example at address 0x30E20000 causes an "Synchronous Abort" exception.

Has someone a hint for me? Is some core clock missing or what else causes the exception?