From: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> Date: Tue, 12 May 2020 23:10:55 +0200 > The Ethernet TX performance has been historically bad on Meson8b and > Meson8m2 SoCs because high packet loss was seen. I found out that this > was related (yet again) to the RGMII TX delay configuration. > In the process of discussing the big picture (and not just a single > patch) [0] with Andrew I discovered that the IP block behind the > dwmac-meson8b driver actually seems to support the configuration of the > RGMII RX delay (at least on the Meson8b SoC generation). > > Since I sent the first RFC I got additional documentation from Jianxin > (many thanks!). Also I have discovered some more interesting details: > - Meson8b Odroid-C1 requires an RX delay (by either the PHY or the MAC) > Based on the vendor u-boot code (not upstream) I assume that it will > be the same for all Meson8b and Meson8m2 boards > - Khadas VIM2 seems to have the RX delay built into the PCB trace > length. When I enable the RX delay on the PHY or MAC I can't get any > data through. I expect that we will have the same situation on all > GXBB, GXM, AXG, G12A, G12B and SM1 boards. Further clarification is > needed here though (since I can't visually see these lengthened > traces on the PCB). This will be done before sending patches for > these boards. ... Series applied to net-next, thanks Martin.
