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Message-ID: <e63c2332-ade2-4c93-be21-a550125c543e@alliedtelesis.co.nz> Date: Wed, 18 Jun 2025 21:27:47 +0000 From: Chris Packham <Chris.Packham@...iedtelesis.co.nz> To: "markus.stockhausen@....de" <markus.stockhausen@....de>, 'Andrew Lunn' <andrew@...n.ch> CC: "hkallweit1@...il.com" <hkallweit1@...il.com>, "linux@...linux.org.uk" <linux@...linux.org.uk>, "davem@...emloft.net" <davem@...emloft.net>, "edumazet@...gle.com" <edumazet@...gle.com>, "kuba@...nel.org" <kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>, "michael@...sekall.de" <michael@...sekall.de>, "daniel@...rotopia.org" <daniel@...rotopia.org>, "netdev@...r.kernel.org" <netdev@...r.kernel.org> Subject: Re: AW: [PATCH] net: phy: realtek: convert RTL8226-CG to c45 only Hi Markus, On 18/06/2025 18:03, markus.stockhausen@....de wrote: >> Von: Andrew Lunn <andrew@...n.ch> >> Gesendet: Dienstag, 17. Juni 2025 17:36 >> An: Markus Stockhausen <markus.stockhausen@....de> >> Betreff: Re: [PATCH] net: phy: realtek: convert RTL8226-CG to c45 only >> >> On Tue, Jun 17, 2025 at 11:01:47AM -0400, Markus Stockhausen wrote: >>> The RTL8226-CG can be found on devices like the Zyxel XGS1210-12. These >>> are driven by a RTL9302B SoC that has active phy hardware polling in >>> the background. >> It would be a lot better to just turn that polling off. I have experimented with turning the polling off on my board but it tends to make other switch things not work. The obvious one is the LEDs but I also saw other switching functionality (e.g. packet forwarding, fdb maintenance) stop working. > This is our challenge: https://elixir.bootlin.com/linux/v6.16-rc2/source/drivers/net/mdio/mdio-realtek-rtl9300.c#L366 To be honest I'd never considered dynamically switching between c22 and c45. I've seen mdio controllers busses that can put in either mode as a pinctrl type of operation and if seen PHYs that can be accessed as either c22 or c45 and even support for c45 over c22. But I'd never seen anything that needed to support both at the same time. The only reason I put the restriction in was I didn't want the switch phy polling unit interfering. I also don't have any (working [1]) Realtek hardware with a c22 PHY to test on. I think that perhaps we don't need this restriction as the transfer type is set via SMI_ACCESS_PHY_CTRL_1. I think we would however need to reconcile the other feedback you had around tracking the page number for the c22 accesses which has not been implemented. [1] - I do have a Zyxel board that will probably do the trick but so far I've been unable to get it booting my images. I want to avoid messing up the stock firmware so I haven't tried anything too invasive. >>> As soon as this is active and set to c45 most c22 >>> register accesses are blocked and will stop working. Convert the >>> phy to a c45-only function set. >>> >>> For documentation purposes some register extracts that where taken to >>> verify proper detection. >> Please could you show us the output from ethtool before/after. >> >>> PHY_ID_MATCH_EXACT(0x001cc838), >>> .name = "RTL8226-CG 2.5Gbps PHY", >>> - .get_features = rtl822x_get_features, >> You can see this calls genphy_read_abilities(phydev) at the end, so >> reading information about 10/100/1G speeds, using the standard C22 >> registers. >> >>> - .config_aneg = rtl822x_config_aneg, >>> - .read_status = rtl822x_read_status, >>> - .suspend = genphy_suspend, >>> - .resume = rtlgen_resume, >>> + .soft_reset = rtl822x_c45_soft_reset, >>> + .get_features = rtl822x_c45_get_features, >> This only calls genphy_c45_pma_read_abilities(). So i expect 10/100/1G >> is missing. > I had to patch the mdio driver to make the existing RTL8226 phy driver work > with > It. So whenever a c22 command is sent it will toggle the protocol. I do not > believe > that this is what it was designed for but maybe Chris has some more > experience. I don't know one way or the other if swapping between c22 and c45 is a thing that the hardware allows. It's not something the driver I wrote supports but it could possibly be added by removing the check and unconditionally supplying the required read/write functions. To play nicely with the PPU it would need to track the PHY page accesses like the openWRT implementation does. > > Output with patched bus: > > [ 49.552627] toggle bus 1 from c45 to c22 to read port 24 page 0 register > 1 > [ 49.560663] toggle bus 1 from c22 to c45 > ... > # ethtool lan9 > Settings for lan9: > Supported ports: [ TP MII ] > Supported link modes: 10baseT/Half 10baseT/Full > 100baseT/Half 100baseT/Full > 1000baseT/Full > 2500baseT/Full > Supported pause frame use: Symmetric Receive-only > Supports auto-negotiation: Yes > Supported FEC modes: Not reported > Advertised link modes: 10baseT/Half 10baseT/Full > 100baseT/Half 100baseT/Full > 1000baseT/Full > 2500baseT/Full > Advertised pause frame use: Symmetric Receive-only > Advertised auto-negotiation: Yes > Advertised FEC modes: Not reported > Speed: Unknown! > Duplex: Unknown! (255) > Port: Twisted Pair > PHYAD: 24 > Transceiver: external > Auto-negotiation: on > MDI-X: Unknown > Supports Wake-on: d > Wake-on: d > Link detected: no > > The RTL8226 seems to support proper MDIO_PMA_EXTABLE flags. > So genphy_c45_pma_read_abilities() can conveniently call > genphy_c45_pma_read_ext_abilities() and 10/100/1000 is > populated right. > > Outputs with patched driver: > > # ethtool lan9 > Settings for lan9: > Supported ports: [ TP ] > Supported link modes: 10baseT/Half 10baseT/Full > 100baseT/Half 100baseT/Full > 1000baseT/Full > 2500baseT/Full > Supported pause frame use: Symmetric Receive-only > Supports auto-negotiation: Yes > Supported FEC modes: Not reported > Advertised link modes: 10baseT/Half 10baseT/Full > 100baseT/Half 100baseT/Full > 1000baseT/Full > 2500baseT/Full > Advertised pause frame use: Symmetric Receive-only > Advertised auto-negotiation: Yes > Advertised FEC modes: Not reported > Speed: Unknown! > Duplex: Unknown! (255) > Port: Twisted Pair > PHYAD: 24 > Transceiver: external > Auto-negotiation: on > MDI-X: Unknown > Supports Wake-on: d > Wake-on: d > Link detected: no > > Markus
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