On Mon, Feb 26, 2024 at 10:51:36PM +0800, Shengyu Qu wrote: > Hi Russell, > > 在 2024/2/26 22:39, Russell King (Oracle) 写道: > > On Mon, Feb 26, 2024 at 10:16:46PM +0800, Shengyu Qu wrote: > > > Hi Russell, > > > > > > > On Mon, Feb 26, 2024 at 09:23:46PM +0800, Shengyu Qu wrote: > > > > > ODI DFP-34X-2C2 is capable of 2500base-X, but incorrectly report its > > > > > capabilities in the EEPROM. > > > > > So use sfp_quirk_2500basex for this module to allow 2500Base-X mode. > > > > This was previously submitted by Sergio Palumbo, and comes in two > > > > different forms - an OEM version and non-OEM. There was extensive > > > > discussion about this, and the result is that I'm not accepting this > > > > quirk for this module. > > > > > > > > The reason is that the module _defaults_ to 1000base-X and requires > > > > manual reconfiguration by the user to operate at 2500base-X. > > > > Unfortunately, there is no way for the kernel to know whether that > > > > reconfiguration has occurred. > > > No, In the firmware of this stick, the speed rate is configured to auto > > > negotiation rather than fixed 1000base-X. > > > > How does this "auto negotiation" work? > > > > I mean *exactly* how does it work? How does it know whether the host is > > operating at 1000base-X or 2500base-X? > > > > There is *no* inband protocol to allow this to be negotiated. > > > Well, that seems some kind weird trick implemented in that chip's SDK (maybe > hardware?). It would automatically detect the speed rate that host uses and > switch to that rate. The system log of the stick shows that. This sounds racy - between the SFP detecting the speed of the host and the kernel code reconfiguring the interface. More details please... -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
