linux-kernel - Re: [PATCH 1/2] net: phy: realtek: add logging for the RGMII TX delay configuration

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Message-ID: <e21320b3-6e99-25a4-20d9-e8c5aa1aff03@gmail.com>
Date:   Thu, 26 Dec 2019 12:54:42 -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 1/2] net: phy: realtek: add logging for the RGMII TX delay
 configuration



On 12/26/2019 10:51 AM, Martin Blumenstingl wrote:
> RGMII requires a delay of 2ns between the data and the clock signal.
> There are at least three ways this can happen. One possibility is by
> having the PHY generate this delay.
> This is a common source for problems (for example with slow TX speeds or
> packet loss when sending data). The TX delay configuration of the
> RTL8211F PHY can be set either by pin-strappping the RXD1 pin (HIGH
> means enabled, LOW means disabled) or through configuring a paged
> register. The setting from the RXD1 pin is also reflected in the
> register.
> 
> Add debug logging to the TX delay configuration on RTL8211F so it's
> easier to spot these issues (for example if the TX delay is enabled for
> both, the RTL8211F PHY and the MAC).
> This is especially helpful because there is no public datasheet for the
> RTL8211F PHY available with all the RX/TX delay specifics.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

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