On 2/17/23 17:25, Cristian Ciocaltea wrote: > 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. As the non-coherent DMA work this series depended on has been completed, I started to investigate further the "rgmii-id" issue. I couldn't spot anything wrong in the Motorcomm PHY driver, but eventually got this working by adjusting rx-internal-delay-ps. Will do some more testing before submitting v2. Thanks, Cristian
