diff options
author | Claudiu Manoil <claudiu.manoil@freescale.com> | 2013-02-14 05:00:07 +0000 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2013-02-14 13:32:25 -0500 |
commit | ba7797119b486bb5992beda74bdb26be9a291b46 (patch) | |
tree | b694530d4f62a4e28d60313b57e1c98bfa24bf56 /drivers/net/ethernet/freescale/gianfar.h | |
parent | 13f228da40cacdb3c4c23c8e1272c2ad37d1e4c0 (diff) |
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>
Diffstat (limited to 'drivers/net/ethernet/freescale/gianfar.h')
-rw-r--r-- | drivers/net/ethernet/freescale/gianfar.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/net/ethernet/freescale/gianfar.h b/drivers/net/ethernet/freescale/gianfar.h index 1e2ce8bfea83..63a28d294e20 100644 --- a/drivers/net/ethernet/freescale/gianfar.h +++ b/drivers/net/ethernet/freescale/gianfar.h @@ -1056,6 +1056,7 @@ struct gfar_private { enum gfar_errata errata; unsigned int rx_buffer_size; + u16 uses_rxfcb; u16 padding; /* HW time stamping enabled flag */ |