linuxppc-dev.lists.ozlabs.org archive mirror
 help / color / mirror / Atom feed
* [PATCH v2] gianfar: Fall back to software tcp/udp checksum on older controllers
@ 2011-03-17  3:57 Alex Dubov
  2011-03-18 22:15 ` David Miller
  0 siblings, 1 reply; 3+ messages in thread
From: Alex Dubov @ 2011-03-17  3:57 UTC (permalink / raw)
  To: linux-kernel; +Cc: netdev, linuxppc-dev, davem, mlcreech

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      

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH] gianfar: Fall back to software tcp/udp checksum on older controllers
@ 2011-01-27  9:51 Anton Vorontsov
  2011-01-28  4:37 ` [PATCH v2] " Alex Dubov
  0 siblings, 1 reply; 3+ messages in thread
From: Anton Vorontsov @ 2011-01-27  9:51 UTC (permalink / raw)
  To: Alex Dubov; +Cc: linuxppc-dev, davem, mlcreech

Hello Alex,

On Thu, Jan 27, 2011 at 12:14:21AM -0800, Alex Dubov wrote:
> As specified by errata eTSEC49 of MPC8548 and errata eTSEC12 of MPC83xx,
> older revisions of gianfar controllers will be unable to calculate a TCP/UDP
> packet checksum for some aligments of the appropriate FCB. This patch checks
> for FCB alignment on such controllers and falls back to software checksumming
> if the aligment is known to be bad.
> 
> Signed-off-by: Alex Dubov <oakad@yahoo.com>
> ---
> This is my, somewhat different approach to Matthew Creech proposed solution.
> 
>  drivers/net/gianfar.c |   21 +++++++++++++++++++--
>  drivers/net/gianfar.h |    1 +
>  2 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
> index 5ed8f9f..b4f0e99 100644
> --- a/drivers/net/gianfar.c
> +++ b/drivers/net/gianfar.c
> @@ -950,6 +950,11 @@ static void gfar_detect_errata(struct gfar_private *priv)
>  			(pvr == 0x80861010 && (mod & 0xfff9) == 0x80c0))
>  		priv->errata |= GFAR_ERRATA_A002;
>  
> +	/* MPC8313 Rev < 2.0, MPC8548 rev 2.0 */
> +	if ((pvr == 0x80850010 && mod == 0x80b0 && rev < 0x0020)
> +	    || (pvr == 0x80210020 && mod == 0x8030 && rev == 0x0020))

Please indent it like the above: with two tabs. This is
to keep things consistent.

> +		priv->errata |= GFAR_ERRATA_12;
> +
>  	if (priv->errata)
>  		dev_info(dev, "enabled errata workarounds, flags: 0x%x\n",
>  			 priv->errata);
> @@ -2156,8 +2161,20 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
>  	/* Set up checksumming */
>  	if (CHECKSUM_PARTIAL == skb->ip_summed) {
>  		fcb = gfar_add_fcb(skb);
> -		lstatus |= BD_LFLAG(TXBD_TOE);
> -		gfar_tx_checksum(skb, fcb);
> +		switch (unlikely(gfar_has_errata(priv, GFAR_ERRATA_12))
> +			? 1 : 0) {

The switch construction is quite bizarre. ;-) Why not

if (gfar_has_errata() && (ulong)fcb % 0x20 > 18) {
	csum_help();
} else {
	lstatus |=...
	tx_csum();
}

?

Thanks,

> +		case 1:
> +			/* as specified by errata */
> +			if (((unsigned long)fcb % 0x20) > 0x18) { 
> +				__skb_pull(skb, GMAC_FCB_LEN);
> +				skb_checksum_help(skb);
> +				break;
> +			}
> +			/* otherwise, fall through */
> +		default:
> +			lstatus |= BD_LFLAG(TXBD_TOE);
> +			gfar_tx_checksum(skb, fcb);
> +		}
>  	}

-- 
Anton Vorontsov
Email: cbouatmailru@gmail.com

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2011-03-18 22:14 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-03-17  3:57 [PATCH v2] gianfar: Fall back to software tcp/udp checksum on older controllers Alex Dubov
2011-03-18 22:15 ` David Miller
  -- strict thread matches above, loose matches on Subject: below --
2011-01-27  9:51 [PATCH] " Anton Vorontsov
2011-01-28  4:37 ` [PATCH v2] " Alex Dubov

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).