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The information that may help you is stated in section 9.3.11, on pages 592, 593, and 594 of the Intel (R) Ethernet I210 Datasheet document # 333016. This document can be found at:
Hello, dear Maecenas.
My curent sulution is to write 0x8200 value to BARCTRL register (default value is 0x8700). This BARCTRL register is r/w (i210 Chapter 8.6.12) and reserved but it's the only solution to start with imx6q/PI7c/4xi210 configuration. The reason to write BARCTRL is imx6q hardware PCIe I/O memory 16Mb limit. IGB kernel module and EEPROM Access Tool can't start without reduced BARCTRL.FLBARSize = 010b ( 512Kb I/O memory). Default value BARCTRL.FLBARSize = 111b ( 16Mb I/O memory).