Re: [PATCH] gianfar: Revive the driver for eTSEC devices (disable timestamping)

[David Miller <davem@davemloft.net>]

From: Anton Vorontsov <avorontsov@mvista.com>
Date: Wed, 9 Jun 2010 23:32:19 +0400

> Since commit cc772ab7cdcaa24d1fae332d92a1602788644f7a ("gianfar: Add
> hardware RX timestamping support"), the driver no longer works on
> at least MPC8313ERDB and MPC8568EMDS boards (and possibly much more
> boards as well).
> 
> That's how MPC8313 Reference Manual describes RCTRL_TS_ENABLE bit:
> 
>   Timestamp incoming packets as padding bytes. PAL field is set
>   to 8 if the PAL field is programmed to less than 8. Must be set
>   to zero if TMR_CTRL[TE]=0.
> 
> I see that the commit above sets this bit, but it doesn't handle
> TMR_CTRL. Manfred probably had this bit set by the firmware for
> his boards. But obviously this isn't true for all boards in the
> wild.
> 
> Also, I recall that Freescale BSPs were explicitly disabling the
> timestamping because of a performance drop.
> 
> For now, the best way to deal with this is just disable the
> timestamping, and later we can discuss proper device tree bindings
> and implement enabling this feature via some property.
> 
> Signed-off-by: Anton Vorontsov <avorontsov@mvista.com>

Agreed, applied, thanks Anton.