quoted

@@ -604,6 +604,7 @@ enum spd_duplex {
  	FORCE_100M_FULL,
  	FORCE_1000M_FULL,
  	NWAY_2500M_FULL,
+	NWAY_5000M_FULL,
  };
  /* OCP_ALDPS_CONFIG */

@@ -725,6 +726,7 @@ enum spd_duplex {
  #define BP4_SUPER_ONLY		0x1578	/* RTL_VER_04 only */
  enum rtl_register_content {
+	_5000bps	= BIT(12),

Based on other Realtek chips, I guess that BIT(11_ corresponds to 2500 Mbps
over two twisted pairs. Realtek calls this 5G Lite. Similarly, there are
2.5G Lite and 1G Lite, offering 1250 Mbps and 500 Mbps, respectively, over
two pairs of wires.

Oh, that is different. Normally for a -T2 link, you double the clock
frequency, so you keep the normal bandwidth. But you are saying it
does 500Base-T2, 1250Base-T2, 2500Base-T2?

Can it select these modes on its own, if the link partner is another
Realtek device? Many 1G PHYs will detect if a pair is broken and
downshift to 100Mbps, which only require two working pairs. But this
device has the option of downshifting to 500M.

	Andrew