i.MX ProcessorsのトピックAR8035's RGMII TX CLK delay control

AR8035's RGMII TX CLK delay control

bakbad — Wed, 09 Oct 2019 03:00:14 GMT

Hello NXP,

We had a customed board with iMX6Q and AR8035, there is a problem with network module, while ping the other host in local area, the lost package could reach 15%~25%. And we found that AR8035's RGMII AC timing did not satisfied, RX_CLK and RXD[3:0] is okay, but GTX_CLK and TXD[3:0] is not meetting.

I had see the registers value in ar8035, it seems that the RGMII TX CLOCK delay control had enabled, but from the picture captured by oscilloscope we can't say that. Did i miss something?

Regards,

bo xu

Re: AR8035's RGMII TX CLK delay control

igorpadykov — Wed, 09 Oct 2019 05:34:38 GMT

Hi bo

unfortunately from i.MX6Q delays are not software configurable, according to

sect.4.12.5.3 RGMII Signal Switching Specifications i.MX 6Dual/6Quad Applications Processors for Consumer Products - Data Sheet

"For all versions of RGMII prior to 2.0; This implies that PC board design will require

clocks to be routed such that an additional delay of greater than 1.2 ns and less than 1.7 ns

will be added to the associated clock signal. For 10/100, the max value is unspecified."

For AR8035 delays programming one can look on

Re: Quirks of the Atheros 8035 PHY — Netdev

Best regards
igor
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Re: AR8035's RGMII TX CLK delay control

bakbad — Wed, 09 Oct 2019 11:19:41 GMT

Hi igor

Thanks a lot, I'll try if there are other ways.

Regards

bo xu