On 25/03/2021 08:12, Joakim Zhang wrote: ... >>>>> You mean one of your boards? Does other boards with STMMAC can work >>>> fine? >>>> >>>> We have two devices with the STMMAC and one works OK and the other >> fails. >>>> They are different generation of device and so there could be some >>>> architectural differences which is causing this to only be seen on one device. >>> It's really strange, but I also don't know what architectural differences could >> affect this. Sorry. I realised that for the board which fails after this change is made, it has the IOMMU enabled. The other board does not at the moment (although work is in progress to enable). If I add 'iommu.passthrough=1' to cmdline for the failing board, then it works again. So in my case, the problem is linked to the IOMMU being enabled. Does you platform enable the IOMMU? Thanks Jon -- nvpublic