Messages in this thread | | | From | Zhou Yanjie <> | Subject | Question about SC16IS752 device tree. | Date | Tue, 10 May 2022 02:08:28 +0800 |
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Hi folks,
I encountered a problem when using the SC16IS752 to expand the serial port. I connected two Bluetooth modules to the two serial ports extended by the SC16IS752. The device tree is as follows:
&ssi0 { status = "okay";
num-cs = <2>;
pinctrl-names = "default"; pinctrl-0 = <&pins_ssi0>;
sc16is752: expander@0 { compatible = "nxp,sc16is752"; reg = <0>; /* CE0 */
spi-rx-bus-width = <1>; spi-tx-bus-width = <1>; spi-max-frequency = <6000000>;
clocks = <&exclk_sc16is752>;
interrupt-parent = <&gpb>; interrupts = <18 IRQ_TYPE_EDGE_FALLING>;
gpio-controller; #gpio-cells = <2>;
bluetooth@0 { compatible = "brcm,bcm43438-bt"; max-speed = <1000000>;
device-wakeup-gpios = <&gpc 26 GPIO_ACTIVE_HIGH>; reset-gpios = <&gpb 17 GPIO_ACTIVE_LOW>; };
bluetooth@1 { compatible = "brcm,bcm43438-bt";
device-wakeup-gpios = <&gpc 28 GPIO_ACTIVE_HIGH>; reset-gpios = <&gpb 19 GPIO_ACTIVE_LOW>; }; }; };
There are the following error messages after startup:
[ 0.548417] serial serial0-0: controller busy [ 0.553572] serial serial0-0: failure adding device. status -EBUSY [ 0.559764] serial serial0: tty port ttySC0 registered [ 0.565545] spi0.0: ttySC1 at I/O 0x1 (irq = 18, base_baud = 3000000) is a SC16IS752 [ 0.573987] serial serial1-0: controller busy [ 0.578351] serial serial1-0: failure adding device. status -EBUSY [ 0.585003] serial serial1: tty port ttySC1 registered
And only the module connected to the first serial port (ttySC0) can work normally.
If I change the device tree to:
&ssi0 { status = "okay";
num-cs = <2>;
pinctrl-names = "default"; pinctrl-0 = <&pins_ssi0>;
sc16is752: expander@0 { compatible = "nxp,sc16is752"; reg = <0>; /* CE0 */
spi-rx-bus-width = <1>; spi-tx-bus-width = <1>; spi-max-frequency = <6000000>;
clocks = <&exclk_sc16is752>;
interrupt-parent = <&gpb>; interrupts = <18 IRQ_TYPE_EDGE_FALLING>;
gpio-controller; #gpio-cells = <2>;
bluetooth@0 { compatible = "brcm,bcm43438-bt"; max-speed = <1000000>;
device-wakeup-gpios = <&gpc 26 GPIO_ACTIVE_HIGH>; reset-gpios = <&gpb 17 GPIO_ACTIVE_LOW>; }; }; };
Then there will be no error message, and the module connected to the first serial port (ttySC0) can also work normally.
After tracing, the problem seems to be in "serdev_device_add()" (line 111) of "drivers/tty/serdev/core.c":
int serdev_device_add(struct serdev_device *serdev) { struct serdev_controller *ctrl = serdev->ctrl; struct device *parent = serdev->dev.parent; int err;
dev_set_name(&serdev->dev, "%s-%d", dev_name(parent), serdev->nr);
/* Only a single slave device is currently supported. */ if (ctrl->serdev) { dev_err(&serdev->dev, "controller busy\n"); return -EBUSY; } ctrl->serdev = serdev;
err = device_add(&serdev->dev); if (err < 0) { dev_err(&serdev->dev, "Can't add %s, status %pe\n", dev_name(&serdev->dev), ERR_PTR(err)); goto err_clear_serdev; }
dev_dbg(&serdev->dev, "device %s registered\n", dev_name(&serdev->dev));
return 0;
err_clear_serdev: ctrl->serdev = NULL; return err; } EXPORT_SYMBOL_GPL(serdev_device_add);
Is there any way to correctly describe the device mounted on the second serial port (ttySC1) in the device tree? Or how do I need to modify the "drivers/tty/serdev/core.c" to make the SC16IS752 still work properly with two child nodes mounted?
Thanks and beset regards!
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