[PATCH v2 3/3] gianfar: Implement workaround for eTSEC-A002 erratum

[David Miller]

From: Anton Vorontsov <avorontsov at mvista.com>
Date: Wed, 30 Jun 2010 20:39:15 +0400

> MPC8313ECE says:
> 
> "If the controller receives a 1- or 2-byte frame (such as an illegal
>  runt packet or a packet with RX_ER asserted) before GRS is asserted
>  and does not receive any other frames, the controller may fail to set
>  GRSC even when the receive logic is completely idle. Any subsequent
>  receive frame that is larger than two bytes will reset the state so
>  the graceful stop can complete. A MAC receiver (Rx) reset will also
>  reset the state."
> 
> This patch implements the proposed workaround:
> 
> "If IEVENT[GRSC] is still not set after the timeout, read the eTSEC
>  register at offset 0xD1C. If bits 7-14 are the same as bits 23-30,
>  the eTSEC Rx is assumed to be idle and the Rx can be safely reset.
>  If the register fields are not equal, wait for another timeout
>  period and check again."
> 
> Signed-off-by: Anton Vorontsov <avorontsov at mvista.com>

Applied.