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

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Message-ID: <6bb1ba4a-41ba-4bc1-9c4b-abfb27944891@linux.intel.com>
Date: Thu, 11 Jul 2024 18:50:26 +0700
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

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).