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

[Nicolai Buchwitz]

Hi Maxime

On 9.9.2026 09:47, 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@xxxxxxxxxxx>
> ---
>  .../stmicro/stmmac/stmmac_selftests.c         | 33 ++++++++++++++-----
>  1 file changed, 25 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c 
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c
> index 6503678b646e..4564b9f29194 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c

> [...]

> -	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);
> +
> +	memcpy(initial, &priv->xstats, sizeof(*initial));

Is the LPI entry already counted here? AFAIU with tx-lpi-timer=0 on 
dwmac4 the
MAC goes directly into LPI after the frame, before 
stmmac_test_mac_loopback()
returns. The loop below would time out although LPI is working.

Snapshot before the first frame, and take a second snapshot right before
the second loopback for the exit check?

> [...]

> +	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;

nit: -ETIMEDOUT here as well, to match the entry check?

Thanks
Nicolai