Messages in this thread | | | Date | Fri, 17 Feb 2023 17:25:14 +0200 | Subject | Re: [PATCH 07/12] dt-bindings: net: Add StarFive JH7100 SoC | From | Cristian Ciocaltea <> |
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On 2/17/23 15:30, Andrew Lunn wrote: >>> I would actually say it shows we don't understand what is going on >>> with delays. "rgmii" is not every often the correct value. The fact it >>> works suggests the MAC is adding delays. >>> >>> What value are you using for starfive,gtxclk-dlychain ? >> >> This is set to '4' in patch 12/12. >> >>> Try 0 and then "rgmii-id" >> >> I made some more tests and it seems the only stable configuration is "rgmii" >> with "starfive,gtxclk-dlychain" set to 4: >> >> phy-mode | dlychain | status >> ---------+----------+-------------------------------------------- >> rgmii | 4 | OK (no issues observed) >> rgmii-id | 4 | BROKEN (errors reported [1]) >> rgmii | 0 | UNRELIABLE (no errors, but frequent stalls) >> rgmii-id | 0 | BROKEN (errors reported) >> >> [1] Reported errors in case of BROKEN status: >> $ grep '' /sys/class/net/eth0/statistics/* | grep -v ':0$' > > Thanks for the testing. > > So it seems like something is adding delays when it probably should > not. Ideally we want to know what. > > There is a danger here, something which has happened in the past. A > PHY which ignored "rgmii" and actually did power on defaults which was > "rgmii-id". As a result, lots of boards put "rmgii" in there DT blob, > which 'worked'. Until a board came along which really did need > "rgmii". The developer bringing that board up debugged the PHY, found > the problem and made it respect "rgmii" so their board worked. And the > fix broke a number of 'working' boards which had the wrong "rgmii" > instead of "rgmii-id".
Thanks for the heads-up.
> So you have a choice. Go with 4 and "rgmii", but put in a big fat > warning, "Works somehow but is technically wrong and will probably > break sometime in the future". Or try to understand what is really > going on here, were are the delays coming from, and fix the issue. > > Andrew
I will try to analyze this further.
Regards, Cristian
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