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

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hi,

On 9/9/26 13:32, Nicolai Buchwitz wrote:
> 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@bootlin.com>
>> ---
>>  .../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?

I ended up changing my mind and following you call here, V2 is incoming,
hopefully with all the patches this time :)

Maxime

> 
> Thanks
> Nicolai