Linux 4.1.6 [using devicetree] - ESAI configuration problem [i.MX6S based custom board]

[jbd64]

Hi,

We have developed a custom board based on i.MX6 Solo processor, integrating an ADAU1461 CODEC.

We decided to use linux kernel 4.1.6 because ADAU1461 CODEC support comes with it (sound/soc/adau1761* and sound/soc/adau17x1.*).

ADAU1461 CODEC is connected with i.MX6S using i2c for configuration / control and ESAI for the audio data.

As ADAU1461 is not fully supported by Freescale (no machine driver), we created one in sound/soc/fsl directory (file imx-adau1761.c in attachment) inspired by sound/soc/blackfin/bfin-eval-adau1x61.c

In linux, board startup configuration is done using device tree (file imx6s_spu_board.dtsi in attachment).

ADAU1461 CODEC I2C driver is correctly registered and communication with i.MX6Solo by I2C is OK.

ALSA device is also correctly registered as you can see in the linux startup log (call_sequence_audio.txt in attachment).

Hardware connections between i.MX6 ESAI and ADAU1461 are OK.

i.MX6 ESAI is used as Master, so the processor has to generate MCLK clock, using PLL3 Main, PLL3 PFD2, PLL3 PFD3 or PLL4.

Currently, MCLK is our main problem : using alsa tool "aplay" with any audio file, MCLK is not generated.

With an audio file in 44100Hz, aplay terminates with an error : aplay: pcm_write:1737: write error: Input/output error

Not surprising because no MCLK is generated...

As you can see in the device tree code, ESAI fsys clock is configured using PPL3 PFD2 508M clock, and AUDAU1461 CODEC using ESAI PODF (post divisor clock).

First, can you tell us if clock configuration code is already done in linux kernel 4.1.6 in freescale support code, or it needs to be done in a specific alsa component (machine driver, or codec driver...) or in device tree code ? But I don't find any example...

Using devmem in linux, we noted that esai iomux configuration is not done by linux kernel, so we are currently doing it in u-boot startup code.

Are we doing something wrong ? Or is ESAI iomux configuration not supported in linux 4.1.6 version ?

We also want to note that we faced problems configuring I2C, resolved using a weird configuration of SW_PAD_CTL_PAD mux register.

Initially, I2C 3 did not work using this code in device tree :

	pinctrl_i2c3: i2c3grp {
	fsl,pins = <
	MX6QDL_PAD_GPIO_5__I2C3_SCL	0x1b0b0
	MX6QDL_PAD_GPIO_6__I2C3_SDA	0x1b0b0
	>;
	};

So with this code, I2C 3 was not able to generated SCL clock...

After a lot of manipulations and by despair, we tried to add the 0x4000000 bit (inspired by imx6qdl-sabresd.dtsi) in SCL and SDA register value, and it works with it :

	pinctrl_i2c3: i2c3grp {
	fsl,pins = <
	MX6QDL_PAD_GPIO_5__I2C3_SCL	0x4001b8b1
	MX6QDL_PAD_GPIO_6__I2C3_SDA	0x4001b8b1
	>;
	};

As far as I understand, 0x4001b8b1 is written in IOMUXC_SW_PAD_CTL_PAD_GPIO05 for SCL and IOMUXC_SW_PAD_CTL_PAD_GPIO01 for SDA, but the 0x40000000 bit corresponds to a Read-only field... What's the point ? Does the linux code configure something else with this bit ?

After facing this issue, we are wondering if there is the same problem with the ESAI iomux configuration, so it cannot generate the clock ?

As I already mentioned, iomux ESAI configuration is not done by linux kernel with our device tree code, so we cannot modify SW_PAD_CTL_PAD values...

We tried it by u-boot code, but it does not solve the issue...

We are currently stuck with this problem, since a week.

Any idea ?

Thanks a lot,

Original Attachment has been moved to: imx-adau1761.c.zip

Original Attachment has been moved to: call_sequence_audio.txt.zip

Original Attachment has been moved to: imx6s_spu_board.dtsi.zip

[fabio_estevam]

Maybe this commit from 4.3-rc1 can be helpful:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/arch/arm/boot/dts/imx6qdl-sab...

Regards,

Fabio Estevam

[jbd64]

Fabio,

Thank you for your reply.

We modified our device tree imx6s_spu_board.dtsi (file in attachment) and imx6qdl.dtsi inspired by the patch you mentioned.

Using linux version 4.1.6, mclk is still not being generated.

I looked at PAD_CTL_PAD registers used by ESAI, and values 0x1b030 are still not written in these registers...

I am wondering if ESAI is fully supported (with devicetree) in linux 4.1.6 or do we need to use later version, like the latest 4.3 you mentioned ?

[jbd64]

After lots of investigations, we found the problem : it was an hardware one.

We can now provide the clocks from the ESAI configured in Master mode : MCLK, SCK and WS to the ADAU1461 Codec.

We are now facing a problem on the data transmitted from the ESAI to the Codec : the ESAI pin used to transmit data is ESAI_TX2_RX3.

When I launch an aplay command, TE0 from ESAI_TFCR register is activated, so I assume TE0 means ESAI_TX0 pin ?

If so, how can I configure ESAI to use TE2 (I assume ESAI_TX2_RX3) ? Is it the ESAI TDM mode ?

Can you confirm me if we can use ESAI_TX2_RX3 as the first ESAI transmiter pin ?

Thanks a lot,

Regards.