On Wed, Nov 11, 2020 at 11:18 PM Fabio Estevam <feste...@gmail.com> wrote: > > On Wed, Nov 11, 2020 at 11:27 AM Kegl Rohit <keglro...@gmail.com> wrote: > > > > Hello! > > > > We are using a imx6q platform. > > The fec interface is used to receive a continuous stream of custom / > > raw ethernet packets. The packet size is fixed ~132 bytes and they get > > sent every 250µs. > > > > While testing I observed spontaneous packet delays from time to time. > > After digging down deeper I think that the fec peripheral does not > > update the rx descriptor status correctly. > > What is the kernel version that you are using?
Sadly stuck at 3.10.108. https://github.com/gregkh/linux/blob/v3.10.108/drivers/net/ethernet/freescale/fec_main.c The rx queue status handling did not change much compared to 5.x. Only the NAPI handling / clearing IRQs was changed more than once. I also backported the newer NAPI handling style / clearing irqs not in the irq handler but in napi_poll() => same issue. The issue is pretty rare => To reproduce i have to reboot the system every 3 min. Sometimes after 1~2min on the first, sometimes on the ~10th reboot it will happen.
