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fix(lp_core): fix LP UART IOMUX pin not bypassing LP GPIO Matrix for RX

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On chips with SOC_LP_GPIO_MATRIX_SUPPORTED (esp32p4, esp32s31), when the
default IOMUX pin is used for LP UART, calling rtc_gpio_iomux_func_sel()
alone only selects the IOMUX function on the pad side but does not set
sig_in_sel=0 on the peripheral side. This leaves the LP UART RX input
still reading from the LP GPIO Matrix (where no signal is connected),
causing RX to receive nothing.

Apply the same fix that was already in the HP UART driver: use
rtc_gpio_iomux_input() / rtc_gpio_iomux_output() which additionally
configure the peripheral to bypass the LP GPIO Matrix for IOMUX pins.
This commit is contained in:
Sudeep Mohanty
2026-06-16 18:02:54 +08:00
committed by BOT
parent f40e50ee68
commit aa86900364
1 changed files with 19 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files
components/ulp/lp_core/lp_core_uart.c
+19 -10
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@@ -1,5 +1,5 @@
/*
* SPDX-FileCopyrightText: 2023-2025 Espressif Systems (Shanghai) CO LTD
* SPDX-FileCopyrightText: 2023-2026 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
@@ -91,22 +91,31 @@ static esp_err_t lp_uart_config_io(gpio_num_t pin, rtc_gpio_mode_t direction, ui
return ESP_FAIL;
}
/* Set LP_IO direction */
ret = rtc_gpio_set_direction(pin, direction);
if (ret != ESP_OK) {
return ESP_FAIL;
}
/* Connect pins */
const uart_periph_sig_t *upin = &uart_periph_signal[LP_UART_PORT_NUM].pins[idx];
#if !SOC_LP_GPIO_MATRIX_SUPPORTED
/* When LP_IO Matrix is not support, LP_IO Mux must be connected to the pins */
ret = rtc_gpio_iomux_func_sel(pin, upin->iomux_func);
/* On non-matrix chips, LP UART pins are always the default IOMUX pins.
* Use the all-in-one rtc_gpio_iomux APIs which handle func sel and direction. */
if (direction == RTC_GPIO_MODE_OUTPUT_ONLY) {
ret = rtc_gpio_iomux_output(pin, upin->iomux_func);
} else {
ret = rtc_gpio_iomux_input(pin, upin->iomux_func, UART_PERIPH_SIGNAL(LP_UART_PORT_NUM, idx));
}
#else
/* If the configured pin is the default LP_IO Mux pin for LP UART, then set the LP_IO MUX function */
if (upin->default_gpio == pin) {
ret = rtc_gpio_iomux_func_sel(pin, upin->iomux_func);
/* rtc_gpio_iomux_input/output are all-in-one APIs that handle func sel,
* direction, and LP GPIO Matrix bypass in a single call. */
if (direction == RTC_GPIO_MODE_OUTPUT_ONLY) {
ret = rtc_gpio_iomux_output(pin, upin->iomux_func);
} else {
ret = rtc_gpio_iomux_input(pin, upin->iomux_func, UART_PERIPH_SIGNAL(LP_UART_PORT_NUM, idx));
}
} else {
ret = rtc_gpio_set_direction(pin, direction);
if (ret != ESP_OK) {
return ESP_FAIL;
}
/* Select FUNC1 for LP_IO Matrix */
ret = rtc_gpio_iomux_func_sel(pin, 1);
/* Connect the LP_IO to the LP UART peripheral signal */