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-1000Mbps- > >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. 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