i.MX8M EVK - how to make ECSPI2_MOSI (pin E5) an input for PCIe_nWake (M.2 slot)

[daweichen]

Hi NXP,

I have a WiFi module attached to the M.2 slot on the NXP i.MX8M EVK board.  I try to verify the WoWLAN function - i.e. the wireless module can wake the host board in suspend/sleep mode.

NXP i.MX8M schematic shows the following connection.

ECSPI2_MOSI (i.MX8M SoC pin E5) <----------- PCIe_nWake---------->M.2 (Pin55 PEWAKE0) / WiFi Module

I looked at the kernel DTS files for i.MX8M EVK, I did not see ECSPI2_MOSI pin defined in the DTS file.  I assume this pin needs to be defined to be a GPIO input pin and as a wake-source, so that the wireless module can assert the wake signal and wake the host board (EVK board) from suspend/sleep mode through the GPIO/ECSPI2_MOSI pin.

Could NXP please help me with defining this pin in the kernel DTS file?

Thank you very much!

[daweichen]

Would it make sense for me to add the following to the DTS?

wowlan {

  label = "Wake on WLAN";

  gpios = <&gpio5 11 GPIO_ACTIVE_HIGH>

  wakeup-source;

}

[Zhiming_Liu]

The wifi linux driver of IWXXX will use below dts node to configure GPIO5_IO11 as interrupt.There is no need to set the pinctl, please refer the dts we release.

	wifi_wake_host {
		compatible = "nxp,wifi-wake-host";
		interrupt-parent = <&gpio5>;
		interrupts = <11 IRQ_TYPE_LEVEL_LOW>;
		interrupt-names = "host-wake";
	};

 WIFI linux driver:

#ifdef IMX_SUPPORT
/**
*  @brief This function allocates the interrupt line to wakeup
*         the host, and initializes the device for wakeup
*
*   handle  A pointer to moal_handle structure
*
*  @return        N/A
*/
void woal_regist_oob_wakeup_irq(moal_handle *handle)
{
    int ret;
    struct device *dev = handle->hotplug_device;
    struct device_node *node;     ENTER();     node = of_find_compatible_node(NULL, NULL, "nxp,wifi-wake-host");
    if (!node)
        goto err_exit;     handle->irq_oob_wakeup = irq_of_parse_and_map(node, 0);
    if (!handle->irq_oob_wakeup) {
        dev_dbg(dev, "fail to parse irq_oob_wakeup from device tree\n");
        goto err_exit;
    }     ret = devm_request_irq(dev, handle->irq_oob_wakeup,
                   woal_oob_wakeup_irq_handler,
                   IRQF_TRIGGER_LOW | IRQF_SHARED,
                   "wifi_oob_wakeup", handle);
    if (ret) {
        dev_err(dev, "Failed to request irq_oob_wakeup %d (%d)\n",
            handle->irq_oob_wakeup, ret);
        goto err_exit;
    }     disable_irq(handle->irq_oob_wakeup);
    if (device_init_wakeup(dev, true)) {
        dev_err(dev, "fail to init irq_oob_wakeup\n");
        goto err_exit;
    }     LEAVE();
    return; err_exit:
    handle->irq_oob_wakeup = -1;
}

[daweichen]

Thank you!  I ran a test and my M.2 WiFi module failed to wake up the host.  I have not used a scope to monitor the PCIe_nWake waveform yet.

The signal characteristic from the module side is open/drain.  An external 10K pull-up is expected.  I.M8M EVK schematic shows the PCIe_nWake signal line is wired/connects directly to the ECSPI2_MOSI (GPIO5_IO11) pin.  There is no external pull-up of any kind on this signal line.  The DTS, however, enabled internal pull-up (PUE = 1) for the GPIO5_11 pin.

I was wondering if the current design supports the PCIe_nWake signal from the M.2 module without an external 10K pull-up voltage.  Could this be a PAD configuration issue?

Thank you,

DTS:

pinctrl_pcie1: pcie1grp {
fsl,pins = <
...
MX8MQ_IOMUXC_ECSPI2_MOSI_GPIO5_IO11 0x41
>;
};

[Zhiming_Liu]

Hi @daweichen 

Please share your wifi module.

[daweichen]

It's a QCA2066 802.11ax module.

[daweichen]

The signal from the module is open-drain.  An external pull-up is expected. 

Since there is no external pull-up, I am not sure if the internal pull-up on the ECSPI2_MOSI line is adequate.

[Zhiming_Liu]

You should check the QCA2066 driver about this interrupt registration.On the NXP WIFI platform, this function can work.

[Zhiming_Liu]

The dts has defined this interrupt:

	wifi_wake_host {
		compatible = "nxp,wifi-wake-host";
		interrupt-parent = <&gpio5>;
		interrupts = <11 IRQ_TYPE_LEVEL_LOW>;
		interrupt-names = "host-wake";
	};

[daweichen]

The i.MX8M Reference Manual says ECSPI2_MOSI => GPIO5 IO11.  

I would like GPIO5 IO11 to be an input pin and a wake-source.  

Would you be kind enough to help understand correlation between GPIO5 IO11 and the wifi_wake_host declaration block.

&gpio5 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_wifi_reset>;

wl-reg-on-hog {
gpio-hog;
gpios = <29 GPIO_ACTIVE_HIGH>;
output-high;
};
};

pinctrl_wifi_reset: wifiresetgrp {
fsl,pins = <
MX8MQ_IOMUXC_UART4_TXD_GPIO5_IO29 0x16
>;
};