Issues with UART Interface on i.MX93 Custom Board for Bluetooth via NXP 88W9098

[elFunko]

Hello everyone,

I'm currently working on enabling UART communication on a custom i.MX93 board. The UART interface (UART-B) is connected via an M.2 E-Key connector to an EAR00411 Bluetooth/WiFi card, which uses the NXP 88W9098 chipset.

Device Tree Configuration:

For SDIO (USDHC3) and UART (LPUART6), I configured the devicetree as follows:

USDHC3:

&usdhc3 { /* SDIO B */
	pinctrl-names = "default", "state_100mhz", "state_200mhz", "sleep";
	pinctrl-0 = <&pinctrl_usdhc3>, <&pinctrl_usdhc3_wlan>;
	pinctrl-1 = <&pinctrl_usdhc3_100mhz>, <&pinctrl_usdhc3_wlan>;
	pinctrl-2 = <&pinctrl_usdhc3_200mhz>, <&pinctrl_usdhc3_wlan>;
	pinctrl-3 = <&pinctrl_usdhc3_sleep>, <&pinctrl_usdhc3_wlan>;
	mmc-pwrseq = <&usdhc3_pwrseq>;
	vmmc-supply = <&reg_usdhc3_vmmc>;
	bus-width = <4>;
	pm-ignore-notify;
	keep-power-in-suspend;
	non-removable;
	status = "okay";
};

&iomuxc {
	/* need to config the SION for data and cmd pad, refer to ERR052021 */
	pinctrl_usdhc3: usdhc3grp {
		fsl,pins = <
			MX93_PAD_SD3_CLK__USDHC3_CLK		0x1582
			MX93_PAD_SD3_CMD__USDHC3_CMD		0x40001382
			MX93_PAD_SD3_DATA0__USDHC3_DATA0	0x40001382
			MX93_PAD_SD3_DATA1__USDHC3_DATA1	0x40001382
			MX93_PAD_SD3_DATA2__USDHC3_DATA2	0x40001382
			MX93_PAD_SD3_DATA3__USDHC3_DATA3	0x40001382
		>;
	};

	/* need to config the SION for data and cmd pad, refer to ERR052021 */
	pinctrl_usdhc3_100mhz: usdhc3-100mhzgrp {
		fsl,pins = <
			MX93_PAD_SD3_CLK__USDHC3_CLK		0x158e
			MX93_PAD_SD3_CMD__USDHC3_CMD		0x4000138e
			MX93_PAD_SD3_DATA0__USDHC3_DATA0	0x4000138e
			MX93_PAD_SD3_DATA1__USDHC3_DATA1	0x4000138e
			MX93_PAD_SD3_DATA2__USDHC3_DATA2	0x4000138e
			MX93_PAD_SD3_DATA3__USDHC3_DATA3	0x4000138e
		>;
	};

	/* need to config the SION for data and cmd pad, refer to ERR052021 */
	pinctrl_usdhc3_200mhz: usdhc3-200mhzgrp {
		fsl,pins = <
			MX93_PAD_SD3_CLK__USDHC3_CLK		0x15fe
			MX93_PAD_SD3_CMD__USDHC3_CMD		0x400013fe
			MX93_PAD_SD3_DATA0__USDHC3_DATA0	0x400013fe
			MX93_PAD_SD3_DATA1__USDHC3_DATA1	0x400013fe
			MX93_PAD_SD3_DATA2__USDHC3_DATA2	0x400013fe
			MX93_PAD_SD3_DATA3__USDHC3_DATA3	0x400013fe
		>;
	};

	pinctrl_usdhc3_sleep: usdhc3grpsleep {
		fsl,pins = <
			MX93_PAD_SD3_CLK__GPIO3_IO20		0x31e
			MX93_PAD_SD3_CMD__GPIO3_IO21		0x31e
			MX93_PAD_SD3_DATA0__GPIO3_IO22		0x31e
			MX93_PAD_SD3_DATA1__GPIO3_IO23		0x31e
			MX93_PAD_SD3_DATA2__GPIO3_IO24		0x31e
			MX93_PAD_SD3_DATA3__GPIO3_IO25		0x31e
		>;
	};

	pinctrl_usdhc3_wlan: usdhc3wlangrp {
		fsl,pins = <
			MX93_PAD_CCM_CLKO1__GPIO3_IO26		0x31e
		>;
	};
};


/{
	reg_usdhc3_vmmc: regulator-usdhc3 {
		compatible = "regulator-fixed";
		regulator-name = "WLAN_EN";
		regulator-min-microvolt = <3300000>;
		regulator-max-microvolt = <3300000>;
		startup-delay-us = <100>;
		off-on-delay-us = <20000>;
		enable-active-high;
	};

	usdhc3_pwrseq: usdhc3_pwrseq {
		compatible = "mmc-pwrseq-simple";
	};
};

UART:

&lpuart6 { /* UART B */
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart6>;
	status = "okay";
	cts-gpios = <&gpio2 6 GPIO_ACTIVE_LOW>;
	rts-gpios = <&gpio2 7 GPIO_ACTIVE_LOW>;
	uart-has-rtscts;
};

&iomuxc {
	pinctrl_uart6: uart6grp {
		fsl,pins = <
			MX93_PAD_GPIO_IO04__LPUART6_TX			0x11e
			MX93_PAD_GPIO_IO05__LPUART6_RX			0x11e
			MX93_PAD_GPIO_IO06__LPUART6_CTS_B		0x11e
			MX93_PAD_GPIO_IO07__LPUART6_RTS_B		0x11e
		>;
	};
};

In my machine.conf I've added this:

MACHINE_FEATURES:append = " nxp9098-sdio"

KERNEL_MODULE_AUTOLOAD += "moal"
KERNEL_MODULE_PROBECONF += "moal"
module_conf_moal = "options moal mod_para=nxp/wifi_mod_para.conf"

The Bluetooth/WiFi card is correctly detected, and I can see that the nxp9098-sdio driver is loaded in the kernel logs.

Problem:

The issue arises when I attempt to bring up the Bluetooth interface. Using hciattach /dev/ttyLP5 any <baud-rate> flow, I am only able to use a baud rate of up to 115200. Any higher baud rate (e.g., 150000) results in errors such as:

root@imx93:~# hciattach /dev/ttyLP5 any 150000 flow
Device setup complete
[   95.671295] kauditd_printk_skb: 8 callbacks suppressed
[   95.671306] audit: type=1334 audit(1726824428.940:20): prog-id=19 op=LOAD
[   95.683907] audit: type=1334 audit(1726824428.944:21): prog-id=20 op=LOAD
[   95.691189] audit: type=1334 audit(1726824428.952:22): prog-id=21 op=LOAD
[   97.541600] Bluetooth: hci0: command 0x1003 tx timeout
[   97.541602] Bluetooth: hci0: Opcode 0x1003 failed: -110

When using a baud rate of 115200, Bluetooth works correctly:

root@imx93:~# hciattach /dev/ttyLP5 any 115200 flow
Device setup complete
[  212.854117] Bluetooth: MGMT ver 1.22
[  212.945243] NET: Registered PF_ALG protocol Family

root@imx93:~# hciconfig hci0 up
root@imx93:~# hciconfig
hci0:   Type: Primary  Bus: UART
        BD Address: 24:CD:8D:DA:B7:6E  ACL MTU: 1021:7  SCO MTU: 120:6
        UP RUNNING
        RX bytes:1496 acl:0 sco:0 events:91 errors:0
        TX bytes:1269 acl:0 sco:0 commands:91 errors:0

Additional Info:

• Yocto Scarthgap
• Linux Kernel 6.6.28
• Custom i.MX93 module on a custom carrier board

Question:

I understand from the hciattach documentation that "Baudrates higher than 115200bps require vendor-specific initializations that are not implemented for all devices." Could this issue be related to missing initialization for higher baud rates in the driver or configuration? Are there any specific patches or settings I might be missing in my device tree or driver setup for the NXP 88W9098 chipset?

Any help or insights would be greatly appreciated!

Best regards,
Elia

[Rita_Wang · Accepted solution]

To change Bluetooth UART baudrate, please help to try with below commands after you load BT with 115200 and bring up with hciconfig hci0 up

//Example: Change to 3M baud rate, I assume that your Bluetooth device interface is hci0 

root@imx8mqevk:~# hcitool -i hci0 cmd 0x3f 0x0009 0xc0 0xc6 0x2d 0x0
< HCI Command: ogf 0x3f, ocf 0x0009, plen 4
C0 C6 2D 00
> HCI Event: 0x0e plen 4
01 09 FC 00
root@imx8mqevk:~# killall hciattach
root@imx8mqevk:~# [ 524.177184] Bluetooth: hci0: sending frame failed (-49)
root@imx8mqevk:~# killall hciattach
hciattach: no process found
root@imx8mqevk:~#
root@imx8mqevk:~#
root@imx8mqevk:~#
root@imx8mqevk:~# hciattach /dev/ttyLP5  any -s 3000000 3000000 flow
Setting TTY to N_HCI line discipline
Device setup complete 

And below commands are reference for you:

hcitool -i hci0 cmd 0x3f 0x0009 0x00 0x30 0x2a 0x00 ---> set to 2764800  hcitool -i hci0 cmd 0x3f 0x0009 0x20 0x0b 0x20 0x00  hcitool -i hci0 cmd 0x3f 0x0009 0x00 0x20 0x1c 0x00 hcitool -i hci0 cmd 0x3f 0x0009 0x00 0x18 0x15 0x00 hcitool -i hci0 cmd 0x3f 0x0009 0x40 0x42 0x0f 0x00 hcitool -i hci0 cmd 0x3f 0x0009 0x00 0x10 0x0e 0x00

---> set to 2100000 ---> set to 1843200 ---> set to 1382400 --> set to 1000000 ---> set to 921600

[Rita_Wang]

Maybe the moudle you are using set the baud rate of 115200 default. So for others can not work. For support others baud rate you need to modify the BSP. I help assign this question to our WIFI engineer Christine, our WIFI engineer will give support to you in the case 00653265.

Wish you have a nice day