Messages in this thread | | | Date | Thu, 11 May 2023 13:50:30 +0200 | From | Daniel Golle <> | Subject | Re: [PATCH 1/8] net: phy: realtek: rtl8221: allow to configure SERDES mode |
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On Thu, May 11, 2023 at 02:38:19AM +0200, Andrew Lunn wrote: > > +#define RTL8221B_SERDES_OPTION_MODE_2500BASEX_SGMII 0 > > +#define RTL8221B_SERDES_OPTION_MODE_HISGMII_SGMII 1 > > +#define RTL8221B_SERDES_OPTION_MODE_2500BASEX 2 > > So what is 2500BASEX_SGMII? You cannot run SGMII at 2.5G, because > there is no way to repeat a symbol 2.5 times so that a 1G stream takes > up 2.5G bandwidth. The SGMII signalling also does not work at 2.5G.
*_MODE_2500BASEX_SGMII means that the PHY will dynamically switch interface mode between 2500Base-X for 2500M links and SGMII for everything else.
Setting *_MODE_2500BASEX in contrast to that enabled rate-adapter mode and always uses 2500Base-X no matter what the speed of the link on the TP interface is.
I will add a comment explaining that.
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