Re: [PATCH net-next v2 3/3] net: mdio: realtek-rtl9300: Support non-default clock frequency

[Andrew Lunn <andrew@lunn.ch>]

On Sun, Sep 06, 2026 at 10:19:46AM +0200, Markus Stockhausen wrote:
> The ethernet MDIO controller of the Realtek Otto switches has a default
> MDC clock frequency of 2.5MHz. Via configuration bits one can adapt this.
> Depending on the series the following can be set
> 
> - RTL838x: 2.5 Mhz, 10 MHz
> - RTL839x, RTL930x, RTL931x: 1.25 MHz, 2.5 MHz, 5 Mhz
> 
> Enhance the driver so it allows to set the clock frequency via device
> tree. This helps to
> 
> - simplify protocol analysis with a logic analyzer (lower speeds)
> - reduce MDIO access times during normal operation (higher speeds)
> 
> Note: While the devices normally support a per-bus frequency selection,
> the RTL839x is an exception from that. It can only select the speed for
> both buses globally. To avoid device tree special treatment for this,
> use the per-bus speeds for this series too. Return an error if the
> RTL839x Devicetree specifies different frequencies for the first and
> second bus.
> 
> Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew