From: Andrew Lunn <andrew@lunn.ch>
To: Roman Riabenko <roman@riabenko.com>
Cc: wens@kernel.org, jernej.skrabec@gmail.com, samuel@sholland.org,
andre.przywara@arm.com, robh@kernel.org, krzk+dt@kernel.org,
conor+dt@kernel.org, devicetree@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] arm64: dts: allwinner: a64: olinuxino: Fix phy-mode
Date: Sat, 22 Aug 2026 16:53:36 +0200 [thread overview]
Message-ID: <b37fa1dd-862f-48ac-98c9-4556c2bf3f94@lunn.ch> (raw)
In-Reply-To: <20260822052353.22881-1-roman@riabenko.com>
On Sat, Aug 22, 2026 at 08:23:53AM +0300, Roman Riabenko wrote:
> The 'rgmii' mode does not appear to describe the RGMII timing in Olimex
> A64-OlinuXino boards. The PCB layout shows that the clock and data
> traces have roughly the same lengths for both RX and TX and, thus, do
> not appear to implement the 2 ns RGMII delay or introduce any
> significant delay.
>
> According to the KSZ9031RNX datasheet, the PHY adds a typical 1.2 ns RX
> delay and no TX delay by default. The 'rgmii-id' mode causes the PHY
> driver to enable appropriate internal RGMII delays.
>
> Packet loss in the downlink direction is observed with the 'rgmii' mode
> and is severe enough to interfere with downloads and disrupt software
> installation. No packet loss is observed with 'rgmii-id'.
>
> Adjusting the TX delay in the DT was found to be unnecessary with
> 'rgmii-id'.
Nice, thanks for doing a proper analysis.
> Signed-off-by: Roman Riabenko <roman@riabenko.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Andrew
prev parent reply other threads:[~2026-08-22 14:54 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-22 5:23 [PATCH v2] arm64: dts: allwinner: a64: olinuxino: Fix phy-mode Roman Riabenko
2026-08-22 14:53 ` Andrew Lunn [this message]
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