fec_mxc send error while porting fec_mxc driver

[Shengtuo Hu]

Hi,

I was recently porting fec_mxc driver in u-boot to another platform. The
initialization succeeds. However, invoking fec_send always throws the
following error:

> fec_send: status 0x8c00 index 0 ret -22

It looks like that the READY bit of the TX buffer descriptor is not
cleared, but I still do not know why this happens. Does anyone have any
clues about this issue? Thanks!

Here are some register values of the ethernet device when the error happens:

Ethernet state (ecntrl): 0xf0000102 (Active)
TX state (x_des_active): Inactive (no FEC_X_DES_ACTIVE_TDAR bit)
RX state (r_des_active): Inactive (no FEC_R_DES_ACTIVE_RDAR bit)
TX control (x_cntrl): 0x00000004
RX control (r_cntrl): 0x05f20064
RX desc base (erdsr): 0x4e07fd40 (size: 0x600)
TX desc base (etdsr): 0x4e07fdc0
Enabled events (imask): 0x00000000
Pending events (ievent): 0x00000000

Best,
Shengtuo Hu