fec driver works on linux-imx, not linux-fslc+use-mainline-bsp (imx6dl)

Christian Betz


I'm porting a custom MX6DL board from linux-imx to linux-fslc (along with use-mainline-bsp in FEATURES). The primary reason for this choice was for etnaviv support and a general preference for a mainline kernel. I'm pleased to say that the etnaviv is working ok!

Problem: The ethernet connection does not work correctly. It seems to accept pings and I can login via SSH. However, any scp or http transfer fails. Ifconfig shows TX errors. None of these issues happen on linux-imx. btw, i have an imx6qsabresd demo board running linux-fslc with use-mainline-bsp and the ethernet works fine on it.

There are no errors/warnings in dmesg. If I use "ping -s 1500 $DEVICE_IP", I definitely notice pings being lost, so this seems related to packet size somehow.

I'm looking for some suggestions on next steps to troubleshoot this issue, or some idea of what is different between linux-imx and linux-fslc when it comes to the fec driver. Note: i'm running kernel 5.4.46 based on revision 38d6c352 (Otavio's merge on June 15th).

As far as can tell, our ethernet-related customizations are minimal, basically these changes to 'pinctrl_enet' imx6qdl-sabresd.dtsi. Again, these changes seem to work fine on linux-imx but not linux-fslc with use-mainline-bsp.

                pinctrl_enet: enetgrp {
                        fsl,pins = <
                                MX6QDL_PAD_ENET_MDIO__ENET_MDIO         0x1b0b0
                                MX6QDL_PAD_ENET_MDC__ENET_MDC           0x1b0b0
                                MX6QDL_PAD_RGMII_TXC__RGMII_TXC         0x1b030
                                MX6QDL_PAD_RGMII_TD0__RGMII_TD0         0x1b030
                                MX6QDL_PAD_RGMII_TD1__RGMII_TD1         0x1b030
                                MX6QDL_PAD_RGMII_TD2__RGMII_TD2         0x1b030
                                MX6QDL_PAD_RGMII_TD3__RGMII_TD3         0x1b030
                                MX6QDL_PAD_RGMII_TX_CTL__RGMII_TX_CTL   0x1b030
-                               MX6QDL_PAD_ENET_REF_CLK__ENET_TX_CLK    0x1b0b0
+                               /* MX6QDL_PAD_ENET_REF_CLK__ENET_TX_CLK 0x1b0b0
+                                * Changes to CONFIG_BITS
+                                *  Turn off PAD_CTL_HYS, PAT_CTL_PUS_22KUP
+                                *  Turn on SRE_FAST
+                                */
+                               MX6QDL_PAD_ENET_REF_CLK__ENET_TX_CLK    0x100b1
                                MX6QDL_PAD_RGMII_RXC__RGMII_RXC         0x1b030
                                MX6QDL_PAD_RGMII_RD0__RGMII_RD0         0x1b030
                                MX6QDL_PAD_RGMII_RD1__RGMII_RD1         0x1b030
                                MX6QDL_PAD_RGMII_RD2__RGMII_RD2         0x1b030
                                MX6QDL_PAD_RGMII_RD3__RGMII_RD3         0x1b030
                                MX6QDL_PAD_RGMII_RX_CTL__RGMII_RX_CTL   0x1b030
-                               MX6QDL_PAD_GPIO_16__ENET_REF_CLK        0x4001b0a8
+                               /* Completely disable ENET_REF_CLK (???) */
+                               /*MX6QDL_PAD_GPIO_16__ENET_REF_CLK      0x4001b0a8*/

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