Re: [PATCH net-next v6 3/9] net: dsa: realtek: rtl8365mb: set speed for family D

[Linus Walleij]

On Fri, Oct 16, 2026 at 3:03 AM Mieczyslaw Nalewaj <namiltd@xxxxxxxxx> wrote:

> On family C hardware, forcing a 2.5 Gbps link speed requires relying
> strictly on the HSGMII SerDes configuration block, while forcing a dummy
> 1 Gbps value inside the standard digital interface register. Family D
> introduces a dedicated hardware link speed value (5) for 2500M. The speed
> bitfield width has been expanded to 3 bits, splitting the most significant
> bit into a new separate register field (FORCE_SPEED2), which maps directly
> to a distinct per-port digital interface force layout.
>
> On family D the forced-mode configuration (link, duplex, pause, speed)
> is written to a per-port register at 0x12c0 + port instead of the
> per-extint register. The bit positions of TXPAUSE, RXPAUSE, LINK, DUPLEX
> and the low two speed bits are the same as on family C; the upper speed
> bits go to bits 13:12 (FORCE_SPEED2), so FORCE_EN (bit 12 on family C)
> is not set. A second per-port register at 0x12c8 + port enables the
> forced mode: the vendor RTL8367D API writes 0xFFFF there when the MAC
> is forced and 0 otherwise. This driver always forces the MAC, as on
> family C, so it writes 0xFFFF on every call, including link down.
>
> Signed-off-by: Mieczyslaw Nalewaj <namiltd@xxxxxxxxx>

It's pretty terse but I think I get it...

> -               if (speed == SPEED_2500 || speed == SPEED_1000) {
> +               if (speed == SPEED_2500) {
> +                       if (is_d) {
> +                               r_speed = RTL8365MB_D_PORT_SPEED_2500M;
> +                       } else {
> +                               /* The speed field has no value for 2.5 Gbps:
> +                                * the rate is determined by the HSGMII SerDes
> +                                * configuration, and the vendor driver programs
> +                                * the 1 Gbps value here.
> +                                */
> +                               r_speed = RTL8365MB_PORT_SPEED_1000M;
> +                       }

Well what else can we do.

Reviewed-by: Linus Walleij <linusw@xxxxxxxxxx>

Yours,
Linus Walleij