netdev - Re: [PATCH 2/2] net: phy: realtek: add support for configuring the RX delay on RTL8211F

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Date:   Thu, 26 Dec 2019 12:55:23 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        andrew@...n.ch, davem@...emloft.net, netdev@...r.kernel.org,
        linux-amlogic@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] net: phy: realtek: add support for configuring the RX
 delay on RTL8211F



On 12/26/2019 10:51 AM, Martin Blumenstingl wrote:
> On RTL8211F the RX and TX delays (2ns) can be configured in two ways:
> - pin strapping (RXD1 for the TX delay and RXD0 for the RX delay, LOW
>   means "off" and HIGH means "on") which is read during PHY reset
> - using software to configure the TX and RX delay registers
> 
> So far only the configuration using pin strapping has been supported.
> Add support for enabling or disabling the RGMII RX delay based on the
> phy-mode to be able to get the RX delay into a known state. This is
> important because the RX delay has to be coordinated between the PHY,
> MAC and the PCB design (trace length). With an invalid RX delay applied
> (for example if both PHY and MAC add a 2ns RX delay) Ethernet may not
> work at all.
> 
> Also add debug logging when configuring the RX delay (just like the TX
> delay) because this is a common source of problems.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
-- 
Florian