linux/drivers/net/ethernet/freescale
Claudiu Manoil ba7797119b gianfar: Fix and cleanup Rx FCB indication
This fixes a less obvious error on one hand, and prevents futher
similar errors by disambiguating and optimizing RxFCB indication,
on the other hand.

The error consists in NETIF_F_HW_VLAN_TX flag being used as an
indication of Rx FCB insertion. This happened as soon gfar_uses_fcb(),
which despite its name indicates Rx FCB insertion, started
incorporating is_vlan_on().
is_vlan_on(), on the other hand, is also a misleading construct because
we need to differentiate b/w hw VLAN extraction/VLEX (marked by VLAN_RX
flag) and hw VLAN insertion/VLINS (VLAN_TX flag), which are different
mechanisms using different types of FCBs.

The hw spec for the RxFCB feature is as follows:
In the case of RxBD rings, FCBs (Frame Control Block) are inserted by
the eTSEC whenever RCTRL[PRSDEP] is set to a non-zero value. Only one
FCB is inserted per frame (in the buffer pointed to by the RxBD with
bit F set). TOE acceleration for receive is enabled for all rx frames
in this case.

This patch introduces priv->uses_rxfcb field to quickly signal RxFCB
insertion in accordance with the specification above.

The dependency on FSL_GIANFAR_DEV_HAS_TIMER was also eliminated as
another source of confusion. The actual dependency is to priv->hwts_rx_en.
Upon changing priv->hwts_rx_en via IOCTL, the gfar device is being
restarted and on init_mac() the priv->hwts_rx_en flag determines RxFCB
insertion, and rctrl is programmed accordingly. The patch takes care
of this case too.

Though maybe not as self documenting as the inlining version uses_fcb(),
priv->uses_rxfcb has the main purpose to quickly signal, on the hot path,
that the incoming frame has a *Rx* FCB block inserted which needs to be
pulled out before passing the skb to the stack. This is a performance
critical operation, it needs to happen fast, that's why uses_rxfcb is
placed in the first cacheline of gfar_private.
This is also why a cached rctrl cannot be used instead: 1) because
we don't have 32 bits available in the first cacheline of gfar_priv
(but only 16); 2) bit operations are expensive on the hot path.

Signed-off-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-02-14 13:32:25 -05:00
..
fs_enet ethtool: fix drvinfo strings set in drivers 2013-01-06 21:06:31 -08:00
Kconfig NET: FEC: dynamtic check DMA desc buff type 2013-01-04 15:15:39 -08:00
Makefile NET: FEC: dynamtic check DMA desc buff type 2013-01-04 15:15:39 -08:00
fec.c net: fec: correct fix method about miss init spinlock 2013-02-07 23:36:41 -05:00
fec.h net: fec: add napi support to improve proformance 2013-01-29 14:16:17 -05:00
fec_mpc52xx.c net: fec_mpc52xx: Read MAC address from device-tree 2013-02-12 16:15:10 -05:00
fec_mpc52xx.h drivers/net: fix up stale paths from driver reorg 2012-01-30 12:54:40 -05:00
fec_mpc52xx_phy.c
fec_ptp.c net: fec: fix spin_lock dead lock 2013-02-07 23:36:41 -05:00
fsl_pq_mdio.c net/fsl_pq_mdio: add support for the Fman 1G MDIO controller 2012-08-30 13:29:32 -04:00
gianfar.c gianfar: Fix and cleanup Rx FCB indication 2013-02-14 13:32:25 -05:00
gianfar.h gianfar: Fix and cleanup Rx FCB indication 2013-02-14 13:32:25 -05:00
gianfar_ethtool.c gianfar: convert u64 status counters to atomic64_t 2013-02-12 19:08:27 -05:00
gianfar_ptp.c gianfar_ptp: use iomem, not ioports resource tree in probe 2012-10-24 23:18:59 -04:00
gianfar_sysfs.c drivers/net: fix up stale paths from driver reorg 2012-01-30 12:54:40 -05:00
ucc_geth.c net: fix typo in freescale/ucc_geth.c 2012-10-09 00:21:38 -04:00
ucc_geth.h net: remove skb recycling 2012-10-07 00:40:54 -04:00
ucc_geth_ethtool.c ethtool: fix drvinfo strings set in drivers 2013-01-06 21:06:31 -08:00
xgmac_mdio.c net/freescale: remove __dev* attributes 2012-12-03 11:16:54 -08:00