svn commit: r192027 - head/sys/arm/at91

[Stanislav Sedov]

On Thu, 14 May 2009 21:37:12 -0600 (MDT)
"M. Warner Losh" <imp at bsdimp.com> mentioned:

> In message: <200905122114.n4CLEag9033208 at svn.freebsd.org>
>             Stanislav Sedov <stas at FreeBSD.org> writes:
> : @@ -926,6 +937,7 @@ atestart_locked(struct ifnet *ifp)
> :  		 * tell the hardware to xmit the packet.
> :  		 */
> :  		WR4(sc, ETH_TAR, segs[0].ds_addr);
> : +		BARRIER(sc, ETH_TAR, 8, BUS_SPACE_BARRIER_WRITE);
> :  		WR4(sc, ETH_TCR, segs[0].ds_len);
> 
> Why is a barrier needed here?
> 
Writing the TCR register triggers the transmit, so it had to be written
strongly after the TAR register. That's why I added the barrier here.

-- 
Stanislav Sedov
ST4096-RIPE

!DSPAM:4a0cfbe4994291152178454!