Re: [PATCH net-next v1 1/2] net: phy: realtek: add support for RTL8261

[Andrew Lunn]

On Wed, Jun 03, 2026 at 02:32:37AM +0000, Javen wrote:
> Hi, Nicolai
> 
> >> +/* Concatenated 4-bit speed code values (SPD_H << 2 | SPD_L) */
> >> +#define RTL8261X_SPEED_CODE_500M	0x3	/* H=0, L=3 */
> >> +#define RTL8261X_SPEED_CODE_1000M	0x7	/* H=1, L=3 */
> >> +#define RTL8261X_SPEED_CODE_2500M	0x8	/* H=2, L=0 */
> >> +#define RTL8261X_SPEED_CODE_5000M	0x9	/* H=2, L=1 */
> >> +#define RTL8261X_SPEED_500		500
> >
> > 500 MBit/s isnt a standard rate which also isnt represented in ethtool.
> > Is this just for documentation or intended to be used? If yes, how?
> 
> Giga-lite (500M) is a Realtek-proprietary speed: when two Realtek
> PHYs supporting Giga-lite are connected and the higher speed is
> disabled or unstable, auto-negotiation may fall back to 500M. Since
> ethtool has no SPEED_500 definition, the driver reports
> SPEED_UNKNOWN for this case.  So we add this.

Is it negotiated? What bit does it use in which code word page to
accomplish this? Is there a register which can be used to control the
advertisement? Can you see the link partner advertisement for this
bit?

	Andrew