| 29 May 2025 |
 emily | hmm I appear to be the proud owner of the world's first asymmetric DAC cable
[ 5] 0.00-10.00 sec 10.7 GBytes 9.17 Gbits/sec 4220 sender
[ 5] 0.00-10.00 sec 5.12 GBytes 4.40 Gbits/sec sender
| 17:44:07 |
|  raul changed their display name from razterer to raul. | 21:18:57 |
 @uep:matrix.org | Uphill vs downhill packets? | 22:37:15 |
 magic_rb | Yeah, yk light has to work hard to climb up too | 22:38:34 |
| 30 May 2025 |
| emily | K900: unfortunately it seems like the BPI-R4 is in fact not happy with this 1000BASE-T SFP+ I tried:
[59210.630450] sfp sfp1: module Switch SFP 407-BBOS-C rev sn SS6250222040 dc 210527
[59210.731954] mtk_soc_eth 15100000.ethernet sfp-wan: validation with support 00,00000000,00000000,00000000 failed: -EINVAL
[59210.742922] sfp sfp1: sfp_add_phy failed: -EINVAL
| 14:39:37 |
| emily | any clue what might be going on there? | 14:39:47 |
 K900 | Uhhh | 14:39:55 |
| emily | I'll grep the kernel but… | 14:39:57 |
| K900 | Not really | 14:39:58 |
| emily | 🫠 | 14:40:23 |
| emily | I fear "it only works with 10G SFP+s" may actually be true | 14:40:30 |
| emily | hmmm | 14:41:27 |
| K900 | It definitely shouldn't | 14:41:29 |
| emily | Settings for sfp-wan:
Supported ports: [ MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
10000baseT/Full
2500baseX/Full
1000baseKX/Full
10000baseKX4/Full
10000baseKR/Full
1000baseX/Full
10000baseCR/Full
10000baseSR/Full
10000baseLR/Full
10000baseLRM/Full
10000baseER/Full
2500baseT/Full
5000baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10000baseT/Full
10000baseKX4/Full
10000baseKR/Full
10000baseCR/Full
10000baseSR/Full
10000baseLR/Full
10000baseLRM/Full
10000baseER/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Speed: 10Mb/s
Duplex: Half
Port: MII
PHYAD: 0
Transceiver: internal
Auto-negotiation: off
Current message level: 0x000000ff (255)
drv probe link timer ifdown ifup rx_err tx_err
Link detected: no
| 14:41:32 |
| K900 | There might be some weirdness with PCS selection | 14:41:37 |
| emily | could "Advertised link modes" be relevant here? | 14:41:38 |
| emily | it seems like the port should nominally support all of them, but the advertised ones are all 10G? | 14:41:52 |
| emily | I'm not sure I'm fully understanding what those fields mean though | 14:42:04 |
| emily | the one I have a (working) 10G DAC in says:
Settings for sfp-lan:
Supported ports: [ ]
Supported link modes: 2500baseX/Full
1000baseX/Full
10000baseCR/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10000baseCR/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Speed: 10000Mb/s
Duplex: Full
Port: Direct Attach Copper
PHYAD: 0
Transceiver: internal
Auto-negotiation: off
Current message level: 0x000000ff (255)
drv probe link timer ifdown ifup rx_err tx_err
Link detected: yes
| 14:42:29 |
| K900 | Advertised is what it will negotiate to the other end | 14:42:33 |
| emily | I see. so "supported" is what the SFP+ module claims and "advertised" is what the BPI claims? | 14:42:53 |
| K900 | I don't think so | 14:42:58 |
| K900 | I think advertised is what it is configured to negotiate | 14:43:09 |
| K900 | And supported is ... who knows what because the module isn't actually probed | 14:43:21 |
| K900 | Presumably just what the PHY supports? | 14:43:41 |
| emily | it = the BPI or the SFP+? | 14:43:51 |
| emily | I guess the former | 14:43:56 |
| emily | wrt what you're saying about the module not being probed | 14:44:01 |
| K900 | It = the kernel | 14:44:19 |
| K900 | The hardware doesn't decide what to negotiate | 14:44:35 |
