Why does my Transmition is not complete.

[SAman.1]

Hello on my serdev when i set it up the transmition complete is not set:

stm32-usart 4000f000.serial: transmission complete not set

I configurated my device tree like this:

&usart3 {

compatible = "st,stm32-uart", "st,stm32f7-uart", "st,stm32h7-uart";

pinctrl-names = "default", "sleep", "idle";

pinctrl-0 = <&usart3_pins_b>;

pinctrl-1 = <&usart3_sleep_pins_b>;

pinctrl-2 = <&usart3_idle_pins_b>;

uart-has-rtscts;

status = "okay";

ethernet {

compatible = "st,stm32_usart_net";

local-mac-address = [ A0 B0 C0 D0 E0 F0 ];

current-speed = <38400>;

};

};

So in my system it shows up like this:

/sys/devices/platform/soc/4000f000.serial/serial0/serial0-0

• driver
• modalias
• of_node
• power
• subsystem
• uevent

The probe methode of my serdev_device_driver looks like this:

struct stmuart *stm;

u32 speed = 115200;

int ret;

stm = devm_kzalloc(&serdev->dev, sizeof(*stm), GFP_KERNEL);

stm->serdev = serdev;

spin_lock_init(&stm->lock);

INIT_WORK(&stm->tx_work, stmuart_transmit);

serdev_device_set_drvdata(serdev, stm);

serdev_device_set_client_ops(serdev, &stm_serdev_ops);

ret = serdev_device_open(serdev);

if (ret) {

dev_err(&serdev->dev, "Unable to open device\n");

goto free;

}

speed = serdev_device_set_baudrate(serdev, speed);

dev_info(&serdev->dev, "Using baudrate: %u\n", speed);

serdev_device_set_flow_control(serdev, true);

return 0;

My kernel shows me the log when i call the "serdev_device_open" methode. But i can not find something to set options to the serdev_device to avoid it. I looked some other examples and there i also did not find a setting for the device tree. My Kernel is on version 5.4

[SAman.1]

Sorry that i tag you but do you have an idea

@Community member​ 

[SAman.1]

I tried the kernel version 5.10 but the same ressult.

[SAman.1]

I figuret the mistake out and i was able to make a loopback module but now i get this exception:

[33168.807576] ------------[ cut here ]------------

[33168.812054] WARNING: CPU: 0 PID: 1392 at /home/gonzo/projects/SerdevTest/usartHci.c:45 stm_tty_receive+0x4c/0x8c [usartHci]

[33168.823255] Modules linked in: usartHci(OE) cfg80211 snd_soc_cs42l51 snd_soc_hdmi_codec snd_soc_stm32_sai_sub snd_soc_audio_graph_card snd_soc_simple_card_utils snd_soc_stm32_i2s snd_soc_core usb_f_rndis u_ether snd_pcm_dmaengine libcomposite snd_pcm stusb160x typec snd_timer snd stm32_hash stm32_crc32 crypto_engine snd_soc_stm32_sai stm32_cec soundcore sch_fq_codel ipv6 [last unloaded: usartHci]

[33168.858431] CPU: 0 PID: 1392 Comm: kworker/u4:1 Tainted: G    W OE   5.10.10 #2

[33168.866254] Hardware name: STM32 (Device Tree Support)

[33168.871406] Workqueue: events_unbound flush_to_ldisc

[33168.876377] [<c0110824>] (unwind_backtrace) from [<c010c4e0>] (show_stack+0x10/0x14)

[33168.884110] [<c010c4e0>] (show_stack) from [<c0b8319c>] (dump_stack+0xb8/0xcc)

[33168.891335] [<c0b8319c>] (dump_stack) from [<c01249c0>] (__warn+0xec/0x104)

[33168.898295] [<c01249c0>] (__warn) from [<c0b7e65c>] (warn_slowpath_fmt+0x64/0xc4)

[33168.905786] [<c0b7e65c>] (warn_slowpath_fmt) from [<bf1360ec>] (stm_tty_receive+0x4c/0x8c [usartHci])

[33168.915014] [<bf1360ec>] (stm_tty_receive [usartHci]) from [<c06b5574>] (ttyport_receive_buf+0x50/0xf4)

[33168.924410] [<c06b5574>] (ttyport_receive_buf) from [<c0693ef4>] (flush_to_ldisc+0x8c/0xe0)

[33168.932765] [<c0693ef4>] (flush_to_ldisc) from [<c0141798>] (process_one_work+0x1dc/0x59c)

[33168.941032] [<c0141798>] (process_one_work) from [<c0141ba4>] (worker_thread+0x4c/0x520)

[33168.949128] [<c0141ba4>] (worker_thread) from [<c014818c>] (kthread+0x144/0x180)

[33168.956526] [<c014818c>] (kthread) from [<c0100148>] (ret_from_fork+0x14/0x2c)

[33168.963741] Exception stack(0xc3e1dfb0 to 0xc3e1dff8)

[33168.968793] dfa0:                   00000000 00000000 00000000 00000000

[33168.976976] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

[33168.985155] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000

[33168.991879] ---[ end trace 29e46253976aa845 ]---

it only pops up when i sent the data when i just print what i recive i get no error,

my loopack looks like this:

static int

stm_tty_receive(struct serdev_device *serdev, const unsigned char *data,

size_t count)

{

  struct stmuart *stm = serdev_device_get_drvdata(serdev);

int len;

  u8 *pos;

  spin_lock(&stm->lock);

  WARN_ON(stm->tx_left);

  pos = stm->tx_buffer;

  len = serdev_device_write_buf(serdev,

   data, count);

  stm->tx_left = (pos - stm->tx_buffer) - len;

stm->tx_head = stm->tx_buffer + len;

  spin_unlock(&stm->lock);

return len;

}

[SAman.1]

The issue was that my device tree was not setup corectly thats why i had this issue before

[Olivier GALLIEN]

Hi @SAman.1​ ,

Sorry to come late in the thread.

Seems you figure out by yourself the issue.

Could you elaborate further "my device tree was not setup correctly" ?

Which node/properties exactly ?

This may help other members and us in ST to better know where was the trap.

Thanks,

Olivier

[SAman.1]

I needed to enable it on the stm32mp151.dtsi and not in the stm32mp15xx-dkx.dtsi.

But i have a new question when enable serdev_device_set_flow_control(serdev, true); it is not sending and the CTS and RTS not get changed. do i need to enable more to get hardware flow control on a serdev.

[Olivier GALLIEN]

Hi @SAman.1​ 

Maybe this old post can help to setup HW Flow control

https://community.st.com/s/question/0D53W0000037Pi0SAE/how-to-enable-hardware-flow-control-rs485

Olivier

[SAman.1]

Hi I saw that post already but it did not helped me because I wanted to use it from my serial device bus.

[SAman.1]

I am also not able to change my CTS or RTS pin with the serdev_device_set_tiocm methode.