fix esp_modem switch mode timeout

Closes espressif/esp-idf#3506
Closes espressif/esp-idf#4324

Author: suda-morris

examples/protocols/pppos_client/components/modem/include/esp_modem_dce.h

@@ -52,7 +52,7 @@ typedef struct modem_dte modem_dte_t;
  */
 #define MODEM_COMMAND_TIMEOUT_DEFAULT (500)      /*!< Default timeout value for most commands */
 #define MODEM_COMMAND_TIMEOUT_OPERATOR (75000)   /*!< Timeout value for getting operator status */
-#define MODEM_COMMAND_TIMEOUT_MODE_CHANGE (3000) /*!< Timeout value for changing working mode */
+#define MODEM_COMMAND_TIMEOUT_MODE_CHANGE (5000) /*!< Timeout value for changing working mode */
 #define MODEM_COMMAND_TIMEOUT_HANG_UP (90000)    /*!< Timeout value for hang up */
 #define MODEM_COMMAND_TIMEOUT_POWEROFF (1000)    /*!< Timeout value for power down */
 

examples/protocols/pppos_client/components/modem/src/esp_modem.c

@@ -412,6 +412,8 @@ modem_dte_t *esp_modem_dte_init(const esp_modem_dte_config_t *config)
     res = uart_driver_install(esp_dte->uart_port, config->rx_buffer_size, config->tx_buffer_size,
                               config->event_queue_size, &(esp_dte->event_queue), 0);
     MODEM_CHECK(res == ESP_OK, "install uart driver failed", err_uart_config);
+    res = uart_set_rx_timeout(esp_dte->uart_port, 1);
+    MODEM_CHECK(res == ESP_OK, "set rx timeout failed", err_uart_config);
 
     /* Set pattern interrupt, used to detect the end of a line. */
     res = uart_enable_pattern_det_baud_intr(esp_dte->uart_port, '\n', 1, MIN_PATTERN_INTERVAL, MIN_POST_IDLE, MIN_PRE_IDLE);