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From:   Kurt Kanzenbach <kurt@linutronix.de>
To:     Johannes Zink <j.zink@pengutronix.de>,
        Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Richard Cochran <richardcochran@gmail.com>,
        Russell King <linux@armlinux.org.uk>
Cc:     patchwork-jzi@pengutronix.de, netdev@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        kernel@pengutronix.de, kernel test robot <lkp@intel.com>
Subject: Re: [PATCH v3 0/2] net: stmmac: correct MAC propagation delay
In-Reply-To: <9954c171-cb2d-83a4-6965-f5cb3a4a6166@pengutronix.de>
References: <20230719-stmmac_correct_mac_delay-v3-0-61e63427735e@pengutronix.de>
 <87fs51kb4k.fsf@kurt>
 <9954c171-cb2d-83a4-6965-f5cb3a4a6166@pengutronix.de>
Date:   Thu, 03 Aug 2023 12:12:04 +0200
Message-ID: <87a5v8a0zv.fsf@kurt>
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On Wed Aug 02 2023, Johannes Zink wrote:
> Hi Kurt,
>
> On 8/2/23 12:10, Kurt Kanzenbach wrote:
>> On Tue Aug 01 2023, Johannes Zink wrote:
>>> ---
>>> Changes in v3:
>>> - work in Richard's review feedback. Thank you for reviewing my patch:
>>>    - as some of the hardware may have no or invalid correction value
>>>      registers: introduce feature switch which can be enabled in the gl=
ue
>>>      code drivers depending on the actual hardware support
>>>    - only enable the feature on the i.MX8MP for the time being, as the =
patch
>>>      improves timing accuracy and is tested for this hardware
>>> - Link to v2: https://lore.kernel.org/r/20230719-stmmac_correct_mac_del=
ay-v2-1-3366f38ee9a6@pengutronix.de
>>>
>>> Changes in v2:
>>> - fix builds for 32bit, this was found by the kernel build bot
>>> 	Reported-by: kernel test robot <lkp@intel.com>
>>> 	Closes: https://lore.kernel.org/oe-kbuild-all/202307200225.B8rmKQPN-lk=
p@intel.com/
>>> - while at it also fix an overflow by shifting a u32 constant from macr=
o by 10bits
>>>    by casting the constant to u64
>>> - Link to v1: https://lore.kernel.org/r/20230719-stmmac_correct_mac_del=
ay-v1-1-768aa4d09334@pengutronix.de
>>>
>>> ---
>>> Johannes Zink (2):
>>>        net: stmmac: correct MAC propagation delay
>>>        net: stmmac: dwmac-imx: enable MAC propagation delay correction =
for i.MX8MP
>>=20
>> Tested on imx8mp <-> TSN Switch <-> x86 with i225:
>>=20
>> Before your patch:
>>=20
>> |ptp4l -i eth0 -f configs/gPTP.cfg --summary_interval=3D5 -m
>> |ptp4l[139.274]: rms    9 max   27 freq +29264 +/-  13 delay   347 +/-  =
 2
>> |ptp4l[171.279]: rms   10 max   24 freq +29257 +/-  13 delay   344 +/-  =
 2
>> |ptp4l[203.283]: rms   10 max   24 freq +29254 +/-  13 delay   347 +/-  =
 2
>> |ptp4l[235.288]: rms    9 max   24 freq +29255 +/-  13 delay   346 +/-  =
 1
>> |ptp4l[267.292]: rms    9 max   28 freq +29257 +/-  13 delay   347 +/-  =
 2
>>=20
>> After:
>>=20
>> |ptp4l -i eth0 -f configs/gPTP.cfg --summary_interval=3D5 -m
>> |ptp4l[214.186]: rms    9 max   29 freq +28868 +/-  16 delay   326 +/-  =
 2
>> |ptp4l[246.190]: rms    8 max   22 freq +28902 +/-  15 delay   329 +/-  =
 2
>> |ptp4l[278.194]: rms    9 max   24 freq +28930 +/-  15 delay   325 +/-  =
 1
>> |ptp4l[310.199]: rms    9 max   25 freq +28956 +/-  15 delay   327 +/-  =
 3
>> |ptp4l[342.203]: rms    9 max   27 freq +28977 +/-  14 delay   327 +/-  =
 1
>>=20
>> And the derived register values:
>>=20
>> |[   15.864016] KURT: PTP_TS_INGR_CORR_NS: 3147483248 PTP_TS_INGR_CORR_S=
NS: 0
>> |[   15.870862] KURT: PTP_TS_EGR_CORR_NS: 400 PTP_TS_EGR_CORR_SNS: 0
>> |[   20.000962] KURT: PTP_TS_INGR_CORR_NS: 3147483636 PTP_TS_INGR_CORR_S=
NS: 0
>> |[   20.007809] KURT: PTP_TS_EGR_CORR_NS: 12 PTP_TS_EGR_CORR_SNS: 0
>>=20
>> So, seems to work:
>>=20
>> Tested-by: Kurt Kanzenbach <kurt@linutronix.de> # imx8mp
>
> Thank you for testing!
> Johannes

AFAICT from the manuals the MAC propagation delay should be corrected
for the Intel TSN NIC(s) as well. I'll follow up with testing and a
patch when this set is merged.

Thanks,
Kurt

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