Merge branch 'fix/esp_usb_cdc_acm_read_return_val' into 'master'

fix: Fix the ESP USB CDC ACM port read return value

Closes ESF-157 and ESF-145

See merge request espressif/esp-serial-flasher!124

Author: DNedic

examples/esp32_usb_cdc_acm_example/main/main.c

@@ -96,9 +96,6 @@ void app_main(void)
         device_disconnected_sem = xSemaphoreCreateBinary();
         assert(device_disconnected_sem);
 
-        // Delay as target may not be ready to accept commands immediately after connection
-        loader_port_delay_ms(100);
-
         /* The ESP32-S3 ignores the line coding set commands,
            so we don't set the higher baudrate argument */
         if (connect_to_target(0) == ESP_LOADER_SUCCESS) {

port/esp32_usb_cdc_acm_port.c

@@ -156,7 +156,7 @@ esp_loader_error_t loader_port_read(uint8_t *data, const uint16_t size, const ui
 #endif
         return ESP_LOADER_SUCCESS;
     } else {
-        return ESP_LOADER_ERROR_FAIL;
+        return ESP_LOADER_ERROR_TIMEOUT;
     }
 }