diff --git a/drivers/include/periph/gpio_ll.h b/drivers/include/periph/gpio_ll.h
index e8690f002f..280b6f3cc2 100644
--- a/drivers/include/periph/gpio_ll.h
+++ b/drivers/include/periph/gpio_ll.h
@@ -176,7 +176,13 @@ typedef enum {
      * @brief   Disconnect pin from all peripherals
      *
      * The implementation should aim to reduce power consumption of the pin
-     * when this state is entered, if this is feasible.
+     * when this state is entered, if this is feasible. For pins where it is
+     * possible and sensible, this should electrically disconnect them
+     * (high impedance).
+     *
+     * @warning If a given pin will not only be disconnected from peripherals
+     *          but also enter an high impedance state is implementation
+     *          defined and may differ from pin to pin.
      *
      * @note    Pull resistors can still be requested in this mode. This can be
      *          useful e.g. for keeping an UART TXD pin from emitting noise
diff --git a/tests/periph/gpio_ll/README.md b/tests/periph/gpio_ll/README.md
index f2ed1539cb..28ec025f54 100644
--- a/tests/periph/gpio_ll/README.md
+++ b/tests/periph/gpio_ll/README.md
@@ -19,3 +19,11 @@ GPIO port is set via `PORT_IN`. Both `PORT_IN == PORT_OUT` and
 `PORT_IN != PORT_OUT` is valid. The input pin number within `PORT_IN` are set
 via `PIN_IN_0` and `PIN_IN_1`. `PIN_IN_0` has to be wired to `PIN_OUT_0`, and
 `PIN_IN_1` to `PIN_OUT_1`.
+
+## Expected Failures
+
+Implementations are allowed to not electrically disconnect GPIO pins in state
+`GPIO_DISCONNECT`. The test will however test for pins to be electrically
+disconnected. For every MCU supported by GPIO LL so far at least some pins can
+be electrically disconnected. You might need to change the GPIO pins tested
+if the test for disconnected GPIOs being also electrically disconnected.
diff --git a/tests/periph/gpio_ll/main.c b/tests/periph/gpio_ll/main.c
index 03a8423011..9cc9ce42c2 100644
--- a/tests/periph/gpio_ll/main.c
+++ b/tests/periph/gpio_ll/main.c
@@ -470,6 +470,18 @@ static void test_gpio_ll_init(void)
         is_supported = !(gpio_ll_read(port_in) & (1ULL << PIN_IN_0));
         printf_optional("Output can indeed be pulled LOW: %s\n",
                         noyes[is_supported]);
+        /* If this expects fails, try with a different pin. Often pins intended
+         * for use as UART, I2C, or hardware /CS on SPI cannot be configured
+         * as high impedance and will instead remain HIGH. An implementation
+         * is free to work around this e.g. by configuring these pins as
+         * input with the input buffer disabled or as analog input without
+         * routing them to the ADC, or just to restore the reset configuration
+         * and have them high.
+         *
+         * Even though this can fail on some pins, the `expect()` here should
+         * remain. Just test with a different pin that can be configured as
+         * high impedance to confirm that this functionality does work where
+         * supported. */
         expect(is_supported);
     }
     else {
@@ -482,6 +494,10 @@ static void test_gpio_ll_init(void)
         is_supported = (gpio_ll_read(port_in) & (1ULL << PIN_IN_0));
         printf_optional("Output can indeed be pulled HIGH: %s\n",
                         noyes[is_supported]);
+        /* May also fail for some pins, if the reset configuration of the
+         * pin results in LOW output. Do not comment this out, but rather
+         * try with a different pin to confirm that this functionality does
+         * work where supported */
         expect(is_supported);
     }
     else {