[PATCH v2] gianfar: Fall back to software tcp/udp checksum on older controllers

[Alex Dubov <oakad@yahoo.com>]

As specified by errata eTSEC49 of MPC8548 and errata eTSEC12 of MPC83xx,=0A=
older revisions of gianfar controllers will be unable to calculate a TCP/UD=
P=0Apacket checksum for some alignments of the appropriate FCB. This patch =
checks=0Afor FCB alignment on such controllers and falls back to software c=
hecksumming=0Aif the alignment is known to be bad.=0A=0ASigned-off-by: Alex=
 Dubov <oakad@yahoo.com>=0A---=0ACan we, please, proceed with this patch?=
=0AThe issue is badly annoying, breaking quite a few of the MPC8548 chips.=
=0A=0AChanges for v2:=0A   - Make indentation slightly more consistent.=0A =
  - Replace bizarre switch-based condition with plain boring one.=0A=0A dri=
vers/net/gianfar.c |   16 ++++++++++++++--=0A drivers/net/gianfar.h |    1 =
+=0A 2 files changed, 15 insertions(+), 2 deletions(-)=0A=0Adiff --git a/dr=
ivers/net/gianfar.c b/drivers/net/gianfar.c=0Aindex 5ed8f9f..3da19a5 100644=
=0A--- a/drivers/net/gianfar.c=0A+++ b/drivers/net/gianfar.c=0A@@ -950,6 +9=
50,11 @@ static void gfar_detect_errata(struct gfar_private *priv)=0A =09=
=09=09(pvr =3D=3D 0x80861010 && (mod & 0xfff9) =3D=3D 0x80c0))=0A =09=09pri=
v->errata |=3D GFAR_ERRATA_A002;=0A =0A+=09/* MPC8313 Rev < 2.0, MPC8548 re=
v 2.0 */=0A+=09if ((pvr =3D=3D 0x80850010 && mod =3D=3D 0x80b0 && rev < 0x0=
020) ||=0A+=09=09=09(pvr =3D=3D 0x80210020 && mod =3D=3D 0x8030 && rev =3D=
=3D 0x0020))=0A+=09=09priv->errata |=3D GFAR_ERRATA_12;=0A+=0A =09if (priv-=
>errata)=0A =09=09dev_info(dev, "enabled errata workarounds, flags: 0x%x\n"=
,=0A =09=09=09 priv->errata);=0A@@ -2156,8 +2161,15 @@ static int gfar_star=
t_xmit(struct sk_buff *skb, struct net_device *dev)=0A =09/* Set up checksu=
mming */=0A =09if (CHECKSUM_PARTIAL =3D=3D skb->ip_summed) {=0A =09=09fcb =
=3D gfar_add_fcb(skb);=0A-=09=09lstatus |=3D BD_LFLAG(TXBD_TOE);=0A-=09=09g=
far_tx_checksum(skb, fcb);=0A+=09=09/* as specified by errata */=0A+=09=09i=
f (unlikely(gfar_has_errata(priv, GFAR_ERRATA_12)=0A+=09=09=09     && ((uns=
igned long)fcb % 0x20) > 0x18)) {=0A+=09=09=09__skb_pull(skb, GMAC_FCB_LEN)=
;=0A+=09=09=09skb_checksum_help(skb);=0A+=09=09} else {=0A+=09=09=09lstatus=
 |=3D BD_LFLAG(TXBD_TOE);=0A+=09=09=09gfar_tx_checksum(skb, fcb);=0A+=09=09=
}=0A =09}=0A =0A =09if (vlan_tx_tag_present(skb)) {=0Adiff --git a/drivers/=
net/gianfar.h b/drivers/net/gianfar.h=0Aindex 54de413..ec5d595 100644=0A---=
 a/drivers/net/gianfar.h=0A+++ b/drivers/net/gianfar.h=0A@@ -1039,6 +1039,7=
 @@ enum gfar_errata {=0A =09GFAR_ERRATA_74=09=09=3D 0x01,=0A =09GFAR_ERRAT=
A_76=09=09=3D 0x02,=0A =09GFAR_ERRATA_A002=09=3D 0x04,=0A+=09GFAR_ERRATA_12=
=09=09=3D 0x08, /* a.k.a errata eTSEC49 */=0A };=0A =0A /* Struct stolen al=
most completely (and shamelessly) from the FCC enet source=0A-- =0A1.7.3.2=
=0A=0A=0A=0A=0A