Re: [PATCH net v2 2/6] net: stmmac: selftests: Validate EEE based on the actual LPI timer value

[Nicolai Buchwitz <nb@tipi-net.de>]

Hi Maxime,

On 10.9.2026 17:13, Maxime Chevallier wrote:
> The EEE selftest is a 2-step test :
>  - It validates that we enter in LPI mode with the
>    irq_tx_path_in_lpi_mode_n counter
>  - It then validates that we exit LPI when sending a frame, with the
>    irq_tx_path_exit_lpi_mode_n counter.
> 
> The current state of the test lacks 2 main things :
> 
>  - We don't know exactly when was the previous frame sent (it's from 
> the
>    previous selftest)
> 
>  - The timeout is hardcoded, while the LPI is entered after a
>    user-configurable delay. On top of that, the timeout loop uses a
>    pre-decrement iterator (--retries) that actually only iterate nine
>    times, so 900ms while the default LPI value is 1 second.
> 
> Let's therefore make it more deterministic :
> 
>  - Send a frame at the beginning of the test
>  - Wait for more than the lpi timer value, we timeout after about twice
>    the value,
>  - Then send another frame, and verify that we do go out of LPI, also
>    with a timeout.
> 
> Note that the test's goal isn't to validate the LPI timer value itself,
> only that we enter/leave LPI mode.
> 
> Fixes: 091810dbded9 ("net: stmmac: Introduce selftests support")
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> ---
>  .../stmicro/stmmac/stmmac_selftests.c         | 39 +++++++++++++++----
>  1 file changed, 32 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c 
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c
> index 6503678b646e..a8280834185c 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c
> @@ -462,7 +462,7 @@ static int stmmac_test_mmc(struct stmmac_priv 
> *priv)
>  static int stmmac_test_eee(struct stmmac_priv *priv)
>  {
>  	struct stmmac_extra_stats *initial, *final;
> -	int retries = 10;
> +	unsigned long timeout, max_duration;
>  	int ret;
> 
>  	if (!priv->dma_cap.eee || !priv->eee_active)
> @@ -478,14 +478,21 @@ static int stmmac_test_eee(struct stmmac_priv 
> *priv)
>  		goto out_free_initial;
>  	}
> 
> +	/* Snapshot stats, we want to count the in_lpi events. We may enter
> +	 * LPI just after the packet was sent.
> +	 */
>  	memcpy(initial, &priv->xstats, sizeof(*initial));
> 
> +	/* Send a frame, then wait to enter LPI */
>  	ret = stmmac_test_mac_loopback(priv);
>  	if (ret)
>  		goto out_free_final;
> 
> +	max_duration = usecs_to_jiffies(2 * priv->tx_lpi_timer);
> +
>  	/* We have no traffic in the line so, sooner or later it will go LPI 
> */
> -	while (--retries) {
> +	timeout = jiffies + max_duration;
> +	while (!time_after(jiffies, timeout)) {
>  		memcpy(final, &priv->xstats, sizeof(*final));
> 
>  		if (final->irq_tx_path_in_lpi_mode_n >
> @@ -494,20 +501,38 @@ static int stmmac_test_eee(struct stmmac_priv 
> *priv)
>  		msleep(100);
>  	}
> 
> -	if (!retries) {
> +	memcpy(final, &priv->xstats, sizeof(*final));
> +	if (final->irq_tx_path_in_lpi_mode_n <=
> +	    initial->irq_tx_path_in_lpi_mode_n) {
>  		ret = -ETIMEDOUT;
>  		goto out_free_final;
>  	}
> 
> -	if (final->irq_tx_path_in_lpi_mode_n <=
> -	    initial->irq_tx_path_in_lpi_mode_n) {
> -		ret = -EINVAL;
> +	/* Re-snapshot, as we want to measure exit_lpi events. We should be
> +	 * in LPI right now.
> +	 */
> +	memcpy(initial, &priv->xstats, sizeof(*initial));
> +
> +	/* TX something so we go out of LPI */
> +	ret = stmmac_test_mac_loopback(priv);
> +	if (ret)
>  		goto out_free_final;
> +
> +	/* Wait for the exit LPI interrupt */
> +	timeout = jiffies + max_duration;
> +	while (!time_after(jiffies, timeout)) {
> +		memcpy(final, &priv->xstats, sizeof(*final));
> +
> +		if (final->irq_tx_path_exit_lpi_mode_n >
> +		    initial->irq_tx_path_exit_lpi_mode_n)
> +			break;
> +		msleep(100);
>  	}
> 
> +	memcpy(final, &priv->xstats, sizeof(*final));
>  	if (final->irq_tx_path_exit_lpi_mode_n <=
>  	    initial->irq_tx_path_exit_lpi_mode_n) {
> -		ret = -EINVAL;
> +		ret = -ETIMEDOUT;
>  		goto out_free_final;
>  	}

Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de

Thanks,
Nicolai