netdev - Re: [PATCH iwl-next v3] igc: Add MQPRIO offload support

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Date: Wed, 26 Jun 2024 17:02:51 -0700
From: Vinicius Costa Gomes <vinicius.gomes@...el.com>
To: Kurt Kanzenbach <kurt@...utronix.de>, Jesse Brandeburg
 <jesse.brandeburg@...el.com>, Tony Nguyen <anthony.l.nguyen@...el.com>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
 <pabeni@...hat.com>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 "shenjian (K)" <shenjian15@...wei.com>, Simon Horman <horms@...nel.org>,
 intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org, Kurt Kanzenbach
 <kurt@...utronix.de>
Subject: Re: [PATCH iwl-next v3] igc: Add MQPRIO offload support

Kurt Kanzenbach <kurt@...utronix.de> writes:

> Add support for offloading MQPRIO. The hardware has four priorities as well
> as four queues. Each queue must be a assigned with a unique priority.
>
> However, the priorities are only considered in TSN Tx mode. There are two
> TSN Tx modes. In case of MQPRIO the Qbv capability is not required.
> Therefore, use the legacy TSN Tx mode, which performs strict priority
> arbitration.
>
> Example for mqprio with hardware offload:
>
> |tc qdisc replace dev ${INTERFACE} handle 100 parent root mqprio num_tc 4 \
> |   map 0 0 0 0 0 1 2 3 0 0 0 0 0 0 0 0 \
> |   queues 1@0 1@1 1@2 1@3 \
> |   hw 1
>
> The mqprio Qdisc also allows to configure the `preemptible_tcs'. However,
> frame preemption is not supported yet.
>
> Tested on Intel i225 and implemented by following data sheet section 7.5.2,
> Transmit Scheduling.
>
> Signed-off-by: Kurt Kanzenbach <kurt@...utronix.de>
> ---
> Changes in v3:
> - Use FIELD_PREP for Tx ARB (Simon)
> - Add helper for Tx ARB configuration (Simon)
> - Limit ethtool_set_channels when mqprio is enabled (Jian)
> - Link to v2: https://lore.kernel.org/r/20240212-igc_mqprio-v2-1-587924e6b18c@linutronix.de
>
> Changes in v2:
> - Improve changelog (Paul Menzel)
> - Link to v1: https://lore.kernel.org/r/20240212-igc_mqprio-v1-1-7aed95b736db@linutronix.de

Acked-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>

-- 
Vinicius