Introduction
This is part 2 of a series of posts involving a cheap camera module based on the HI3518 SoC, which is available on sites such as Aliexpress. In part 1 I described how to build a new Linux OS image for the module to replace the stock version of Linux that comes pre-installed on the module. The post ended with me showing how to boot the new image, but unfortunately on doing so I found that the Ethernet was not working, and this did not appear to be simply down to the need to configure it in the Linux OS.
It turned out that an issue about the Ethernet not working had already been added to the hi35xx/hi35xx-buildroot repository.
The issue appeared to describe the same problem I experienced, particularly the comment made by briaeros, which said:
"The led is barely orange when buildroot is "on" (as if there are not enough power).
On Uboot , it's brightly orange at start, then stay only green. And on the original firmware the two leds are brightly on."
The comments mention that you have to make sure that you have configured the Ethernet driver to either MII or RMII depending on how the Ethernet Phy chip has been connected to the HI3518. It is not possible to tell from looking at the circuit board how the HI3518 has been connected to the Ethernet Phy chip (in the case of the module I have, a IP101GR) so instead I booted in to the original Linux OS and checked the load3518.sh script. From this I determined that the module was using RMII. I then tried setting the CONFIG_HIETH_MII_RMII_MODE_U and CONFIG_HIETH_MII_RMII_MODE_D options in the Linux kernel to 1 (see the Solution section for how) as suggested in the issue. However this did not have any effect.
The comments mention that you have to make sure that you have configured the Ethernet driver to either MII or RMII depending on how the Ethernet Phy chip has been connected to the HI3518. It is not possible to tell from looking at the circuit board how the HI3518 has been connected to the Ethernet Phy chip (in the case of the module I have, a IP101GR) so instead I booted in to the original Linux OS and checked the load3518.sh script. From this I determined that the module was using RMII. I then tried setting the CONFIG_HIETH_MII_RMII_MODE_U and CONFIG_HIETH_MII_RMII_MODE_D options in the Linux kernel to 1 (see the Solution section for how) as suggested in the issue. However this did not have any effect.
The comments in the issue also suggested looking at the boot options passed to the Linux kernel by U-Boot. However, this did not helped in getting the Ethernet working.
This post covers the steps I took to get the Ethernet working.
