>Subject: RE: [U-Boot] [PATCH] revert "tsec: Force TBI PHY to 1000Mbps >fullduplex in SGMII mode" > >On Wed, 2010-11-17 at 21:13 -0700, Li Yang-R58472 wrote: >> >Subject: Re: [U-Boot] [PATCH] revert "tsec: Force TBI PHY to 1000Mbps >> >full duplex in SGMII mode" >> > >> >Hi Zhao, >> > >> >> In message <1289986984-2314-1-git-send-email-b26...@freescale.com> >> >> you >> >wrote: >> >> > On P2020DS and MPC8572DS, the link to SGMII card which use >> >> > Vitesse >> >> > VSC8234 PHY can't come up. Current TBI PHY >> >> > settings(TBICR_SETTINGS) for SGMII mode cause link problems. >> >> > >> >> > Revert commit 46e91674fb4b6d06c6a4984c0b5ac7d9a16923f4, and fix it. >> > >> >Based on my company's discussions with Freescale and Freescale's >> >appnotes I believe that the current implementation is correct. I >> >make reference to some of this in the original patch: >> >http://old.nabble.com/-U-Boot---PATCH--tsec:-Force-TBI-PHY-to-1000Mbp >> >s- full-duplex-in-SGMII-mode-td26188785.html >> > >> >We use Broadcom PHYs on our boards, which likely has something to do >> >with the discrepancies between the P2020DS/MPC8572DS vs the >> >XPedite5370/XPedite5500. Unless you have additional information that >> >shows that in-band SGMII auto-negotiation does work per the spec I'd >> >prefer to keep the current tsec.c code and add >> >CONFIG_TSEC_TBICR_SETTINGS workarounds to the P2020DS (already done >> >in commit >> >90b5bf211b85eee10c34cbeb907ce381142b7c99?) and MPC8572DS. >> >> >> Hi Peter, >> >> From the App Note you mentioned, I didn't find that the auto-negotiation >can't be used. > >My understanding is that the SGMII link is always at 1000Mbps speed - see >figure 1 from the app note. Additionally look at figure 3. My understand >from it, and the app note's text is that SGMII auto-negotiation doesn't >really occur - its just passing the PHY-side auto-negotiation results to >the Freescale MAC, which software then configures. I'm not sure what the >purpose of the "SGMII auto-negotiation" is - its not really auto- >negotiating and the same information can be read from the PHY via its MDIO >interface, which is what is happening on X-ES boards currently.
I guess the point is to save MDIO signals to the external PHY and read the negotiated result from the internal TBI PHY. > >We were told by a Freescale FAE that SGMII auto-negotiation wasn't >supported, although 1000 BASE-X auto-negotation was (which mirrored our >test results). I can dig up the old emails tomorrow at the office with >the details. > >> Actually we need the auto-negotiation enabled for almost all Freescale >reference boards such as P2020DS, MPC8572DS and P1/P2 RDB boards. If we >disable the auto-negotiation on these boards, the SGMII link won't >work. So I guess it might be more common to use auto-negotiation, and a >fixed 1000M link is more like a special case. I'm not sure what's the >recommended way for SGMII PHY interconnect though. > >And auto-negotation doesn't work on X-ES hardware which all use Broadcom >PHYs - which is why I made the original change after consulting a >Freescale FAE. Its not a huge deal to me either way as long as the >XPedite5370 and XPedite5500 continue to not use SGMII auto-negotiation. >Can someone at Freescale provide a definitive answer about what the proper >SGMII auto-negotiation scheme is? And has anyone used it successfully or >unsuccessfully with a non-Vitesse PHY? > >Best, >Peter _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
