linux-kernel - Re: [PATCH v2 net 0/3] Fixes for Felix DSA driver calculation of tc-taprio guard bands

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Date:   Wed, 07 Sep 2022 13:00:18 +0000
From:   patchwork-bot+netdevbpf@...nel.org
To:     Vladimir Oltean <vladimir.oltean@....com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, xiaoliang.yang_1@....com,
        claudiu.manoil@....com, alexandre.belloni@...tlin.com,
        UNGLinuxDriver@...rochip.com, andrew@...n.ch,
        vivien.didelot@...il.com, f.fainelli@...il.com, michael@...le.cc,
        vinicius.gomes@...el.com, fido_max@...ox.ru,
        colin.foster@...advantage.com, richard.pearn@....com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 net 0/3] Fixes for Felix DSA driver calculation of
 tc-taprio guard bands

Hello:

This series was applied to netdev/net.git (master)
by David S. Miller <davem@...emloft.net>:

On Mon,  5 Sep 2022 20:01:22 +0300 you wrote:
> This series fixes some bugs which are not quite new, but date from v5.13
> when static guard bands were enabled by Michael Walle to prevent
> tc-taprio overruns.
> 
> The investigation started when Xiaoliang asked privately what is the
> expected max SDU for a traffic class when its minimum gate interval is
> 10 us. The answer, as it turns out, is not an L1 size of 1250 octets,
> but 1245 octets, since otherwise, the switch will not consider frames
> for egress scheduling, because the static guard band is exactly as large
> as the time interval. The switch needs a minimum of 33 ns outside of the
> guard band to consider a frame for scheduling, and the reduction of the
> max SDU by 5 provides exactly for that.
> 
> [...]

Here is the summary with links:
  - [v2,net,1/3] net: dsa: felix: tc-taprio intervals smaller than MTU should send at least one packet
    https://git.kernel.org/netdev/net/c/11afdc6526de
  - [v2,net,2/3] net: dsa: felix: disable cut-through forwarding for frames oversized for tc-taprio
    https://git.kernel.org/netdev/net/c/843794bbdef8
  - [v2,net,3/3] net: dsa: felix: access QSYS_TAG_CONFIG under tas_lock in vsc9959_sched_speed_set
    https://git.kernel.org/netdev/net/c/a4bb481aeb9d

You are awesome, thank you!
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