On 14/11/2017 13:40, Måns Rullgård wrote: > Marc Gonzalez wrote: > >> Power entire ethernet block down in ndo_stop(). >> Power it back up in ndo_open() and perform HW init. >> Delete nb8800_dma_stop. > > Leave it alone, please. Not all chips might have a separate power > domain for this. Also, it works just fine on the older chips.
There is no need for separate power domains. The ethernet block is clock-gated when it is held in reset. The reset register is implemented on all tango3, tango4, tango5 chips. nb8800_dma_stop() is a hack. The HW dev has stated that it is not supported. One cannot conclude that it "works fine" just because you've never triggered the error condition. (On tango5, the error condition triggers systematically.) We have several customer bug reports on tango3 and tango4 chips complaining about "broken" ethernet after a link down / link up cycle. They are using a different driver, but it implements the same hack in enet_stop_rx(). There is a high probability that the DMA hack is responsible, and wedged the RX DMA state machine. Since older chips do support the reset register, this patch implements the same method for all tango chips.
