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

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Hi Vinicius,

On 11/7/2024 6:44 am, Vinicius Costa Gomes wrote:
Faizal Rahim <faizal.abdul.rahim@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
---

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@xxxxxxxxx>


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).





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