netdev - Re: [PATCH iwl-net v2 2/3] igc: Fix reset adapter logics when tx mode change

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Message-ID: <2c5a0dcf-f9b0-49da-9dea-0a276fa4a0d9@linux.intel.com>
Date: Wed, 17 Jul 2024 15:02:06 +0800
From: "Abdul Rahim, Faizal" <faizal.abdul.rahim@...ux.intel.com>
To: Vinicius Costa Gomes <vinicius.gomes@...el.com>,
 "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>,
 Jesse Brandeburg <jesse.brandeburg@...el.com>,
 Tony Nguyen <anthony.l.nguyen@...el.com>, Simon Horman <horms@...nel.org>,
 Richard Cochran <richardcochran@...il.com>,
 Paul Menzel <pmenzel@...gen.mpg.de>, Sasha Neftin <sasha.neftin@...el.com>
Cc: intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH iwl-net v2 2/3] igc: Fix reset adapter logics when tx mode
 change



On 12/7/2024 1:10 am, Vinicius Costa Gomes wrote:
> "Abdul Rahim, Faizal" <faizal.abdul.rahim@...ux.intel.com> writes:
> 
>> Hi Vinicius,
>>
>> On 11/7/2024 6:44 am, Vinicius Costa Gomes wrote:
>>> Faizal Rahim <faizal.abdul.rahim@...ux.intel.com> writes:
>>>
>>>> Following the "igc: Fix TX Hang issue when QBV Gate is close" changes,
>>>> remaining issues with the reset adapter logic in igc_tsn_offload_apply()
>>>> have been observed:
>>>>
>>>> 1. The reset adapter logics for i225 and i226 differ, although they should
>>>>      be the same according to the guidelines in I225/6 HW Design Section
>>>>      7.5.2.1 on software initialization during tx mode changes.
>>>> 2. The i225 resets adapter every time, even though tx mode doesn't change.
>>>>      This occurs solely based on the condition  igc_is_device_id_i225() when
>>>>      calling schedule_work().
>>>> 3. i226 doesn't reset adapter for tsn->legacy tx mode changes. It only
>>>>      resets adapter for legacy->tsn tx mode transitions.
>>>> 4. qbv_count introduced in the patch is actually not needed; in this
>>>>      context, a non-zero value of qbv_count is used to indicate if tx mode
>>>>      was unconditionally set to tsn in igc_tsn_enable_offload(). This could
>>>>      be replaced by checking the existing register
>>>>      IGC_TQAVCTRL_TRANSMIT_MODE_TSN bit.
>>>>
>>>> This patch resolves all issues and enters schedule_work() to reset the
>>>> adapter only when changing tx mode. It also removes reliance on qbv_count.
>>>>
>>>> qbv_count field will be removed in a future patch.
>>>>
>>>> Test ran:
>>>>
>>>> 1. Verify reset adapter behaviour in i225/6:
>>>>      a) Enrol a new GCL
>>>>         Reset adapter observed (tx mode change legacy->tsn)
>>>>      b) Enrol a new GCL without deleting qdisc
>>>>         No reset adapter observed (tx mode remain tsn->tsn)
>>>>      c) Delete qdisc
>>>>         Reset adapter observed (tx mode change tsn->legacy)
>>>>
>>>> 2. Tested scenario from "igc: Fix TX Hang issue when QBV Gate is closed"
>>>>      to confirm it remains resolved.
>>>>
>>>> Fixes: 175c241288c0 ("igc: Fix TX Hang issue when QBV Gate is closed")
>>>> Signed-off-by: Faizal Rahim <faizal.abdul.rahim@...ux.intel.com>
>>>> Reviewed-by: Simon Horman <horms@...nel.org>
>>>> ---
>>>
>>> There were a quite a few bugs, some of them my fault, on this part of
>>> the code, changing between the modes in the hardware.
>>>
>>> So I would like some confirmation that ETF offloading/LaunchTime was
>>> also tested with this change. Just to be sure.
>>>
>>> But code-wise, looks good:
>>>
>>> Acked-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
>>>
>>>
>>> Cheers,
>>
>>
>> Tested etf with offload, looks like working correctly.
>>
>> 1. mqprio
>> tc qdisc add dev enp1s0 handle 100: parent root mqprio num_tc 3 \
>> map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \
>> queues 1@0 1@1 2@2 \
>> hw 0
>>
>> No reset adapter observed.
>>
>> 2. etf with offload
>> tc qdisc replace dev enp1s0 parent 100:1 etf \
>> clockid CLOCK_TAI delta 300000 offload
>>
>> Reset adapter observed (tx mode legacy -> tsn).
>>
>> 3. delete qdisc
>> tc qdisc delete dev enp1s0 parent root handle 100
>>
>> Reset adapter observed (tx mode tsn -> legacy).
>>
> 
> That no unexpected resets are happening, is good.
> 
> But what I had in mind was some functional tests that ETF is working. I
> guess that's the only way of knowing that it's still working. Sorry that
> I wasn't clear about that.
> 
> 
> Cheers,

My bad.

Just tested ETF functionality and it is working.

1. On Tx Board
a) mqprio
    tc qdisc add dev enp1s0 handle 100: parent root mqprio num_tc 3 \
    map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \
    queues 1@0 1@1 2@2 \
    hw 0
b) etf with offload
    tc qdisc replace dev enp1s0 parent 100:1 etf \
    clockid CLOCK_TAI delta 300000 offload
c) use UDP TAI app to send packets where tx timestamp is set to
    current_time + 1ms for each packet.

2. On Rx Board
a) Checked .pcap log. Observed that interval duration between each rx
    packet is 1ms


Thanks for your help.