I have a problem with FEC on a custom board with cpu imx6q.
The problem is occured after upgrading the kernel from imx git kernel 3.10.17 to 3.10.31 or 3.10.53 .
FEC throughput at small packets(64Bytes) increased nearly %50 after kernel upgrade, so I want to use the new kernel for the performance reasons.
My problem is :
Under heavy traffic at 64 bytes packets, after a while the fec stops receiveing packets. The transmit seems ok. The only interrupts are MII. There is no RXF interupts.
There is no any error on by examinig error registers.
When I looked at the RDAR register it is 0, means FEC stops putting frames to rings beacuse all the rings seems to be full, indeed they are not full.
If I manually set RDAR bit to 1 the receive operations starts to operate.
I looked the patches from 3.10.17 to 3.10.31 but couldnt find any reason why I dont see the problem at kernel version 3.10.17.
Any help is appreciated.