Re: [PATCH net-next v2 1/2] r8152: Add support for 5Gbit Link Speeds and EEE

[Aleksander Jan Bajkowski <olek2@wp.pl>]

Hi Andrew,

On 19/03/2026 23:46, Andrew Lunn wrote:
>>> @@ -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?

It works exactly like you describe. It’s described in the RTL8156B
datasheet[1] if your interested. To be honest, I’ve never used Lite Mode.
I think it’s disabled by default in the driver.

1. https://www.lcsc.com/datasheet/C41376388.pdf

>
> 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


Best regards,
Aleksander