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Message-Id: <ZYNMBR.VDVV3VHFQBMO1@crapouillou.net>
Date: Mon, 09 May 2022 19:13:47 +0100
From: Paul Cercueil <paul@...pouillou.net>
To: Zhou Yanjie <zhouyanjie@...yeetech.com>
Cc: jringle@...dpoint.com, shc_work@...l.ru,
Rob Herring <robh@...nel.org>,
Paul Boddie <paul@...die.org.uk>,
"H. Nikolaus Schaller" <hns@...delico.com>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
linux-serial@...r.kernel.org,
linux-mips <linux-mips@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Question about SC16IS752 device tree.
Hi Zhou,
Le mar., mai 10 2022 at 02:08:28 +0800, Zhou Yanjie
<zhouyanjie@...yeetech.com> a écrit :
> 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.
I can't say for sure that it's your problem, but your bluetooth nodes
are missing "reg" properties.
Cheers,
-Paul
>
>
>
> 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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