From: Andrew Lunn <andrew@lunn.ch>
To: Stefano Radaelli <stefano.radaelli21@gmail.com>
Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Fabio Estevam <festevam@gmail.com>,
imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org
Subject: Re: [v1] arm64: dts: freescale: imx93-var-som: update eqos support for MaxLinear PHY
Date: Wed, 4 Jun 2025 17:13:43 +0200 [thread overview]
Message-ID: <1d755cbf-4dee-4784-98b7-e72061219e3f@lunn.ch> (raw)
In-Reply-To: <CAK+owog69JktbsBhHZj7ULYXmH_bZ-CO8=QEMqBVc0mjp8jz6g@mail.gmail.com>
On Wed, Jun 04, 2025 at 03:08:09PM +0200, Stefano Radaelli wrote:
> Hi Andrew,
>
> To clarify more precisely: hw team told me that the required 2 ns
> RGMII delays are
> implemented directly in hardware inside the SOM itself, through passive delay
> elements (filters) placed on the RX and TX lines. There is no reliance on PHY
> strap settings or any kind of delay configuration via registers.
>
> This means:
> - The delays are fixed and cannot be changed via software.
> - From the point of view of any carrier board, the interface is
> already timing-compliant.
Great. Please add a comment in the DT explaining this. 99% of the time
'rgmii' is wrong, but this is the 1%. We should make it clear this is
not just another cut/paste error, but very intentional and correct
because of the PCB design.
There is a patch to checkpatch.pl i want to introduce in the next
development cycle which will look for 'rgmii', and if found, look on
the line before for a comment including the word 'PCB'. If it finds
'rgmii' without such a comment it will issue a warning. So it would be
nice to avoid that in your correct case.
Andrew
next prev parent reply other threads:[~2025-06-04 15:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-03 22:14 [v1] arm64: dts: freescale: imx93-var-som: update eqos support for MaxLinear PHY Stefano Radaelli
2025-06-04 1:19 ` Andrew Lunn
2025-06-04 7:37 ` Stefano Radaelli
2025-06-04 12:00 ` Andrew Lunn
2025-06-04 13:08 ` Stefano Radaelli
2025-06-04 15:13 ` Andrew Lunn [this message]
2025-06-04 15:20 ` Stefano Radaelli
2025-06-04 15:29 ` Peng Fan
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