Skip to content

Stop losing USB console output on Zephyr boards #11586

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We鈥檒l occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
tannewt merged 1 commit into from
Oct 13, 2026
Merged

Stop losing USB console output on Zephyr boards #11586

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
30 changes: 30 additions & 0 deletions ports/zephyr-cp/supervisor/usb.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include <zephyr/devicetree.h>
#include <zephyr/drivers/disk.h>
#include <zephyr/drivers/pinctrl.h>
#include <zephyr/drivers/uart.h>
#include <zephyr/kernel.h>
#include <zephyr/usb/usbd.h>
#include <zephyr/usb/class/usbd_msc.h>
Expand Down Expand Up @@ -217,6 +218,21 @@ int _zephyr_disk_ioctl(struct disk_info *disk, uint8_t cmd, void *buff) {
// volatile to avoid the compiler caching stale values.
static volatile bool usb_configured = false;

static const struct device *const console_dev = DEVICE_DT_GET(DT_NODELABEL(cdc_acm_console));
static bool console_dtr = false;
static bool usb_suspended = false;

// With flow control on, the CDC ACM driver's poll_out waits for room in its
// TX buffer instead of dropping output. Use it for the console only while
// the host is connected, awake and holds DTR, as TinyUSB does.
static void update_console_flow_control(void) {
bool on = usb_configured && !usb_suspended && console_dtr;
struct uart_config config = {
.flow_ctrl = on ? UART_CFG_FLOW_CTRL_RTS_CTS : UART_CFG_FLOW_CTRL_NONE,
};
uart_configure(console_dev, &config);
}

static void _msg_cb(struct usbd_context *const ctx, const struct usbd_msg *msg) {
LOG_INF("USBD message: %s", usbd_msg_type_string(msg->type));

Expand All @@ -243,6 +259,20 @@ static void _msg_cb(struct usbd_context *const ctx, const struct usbd_msg *msg)
} else if (msg->type == USBD_MSG_RESET) {
usb_configured = false;
}

if (msg->type == USBD_MSG_SUSPEND) {
usb_suspended = true;
} else if (msg->type == USBD_MSG_RESUME || msg->type == USBD_MSG_RESET) {
usb_suspended = false;
}
if (msg->type == USBD_MSG_RESET) {
console_dtr = false;
} else if (msg->type == USBD_MSG_CDC_ACM_CONTROL_LINE_STATE && msg->dev == console_dev) {
uint32_t dtr = 0;
uart_line_ctrl_get(console_dev, UART_LINE_CTRL_DTR, &dtr);
console_dtr = dtr != 0;
}
update_console_flow_control();
}

void usb_init(void) {
Expand Down
Loading