All of lore.kernel.org
 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
  0 siblings, 0 replies; 7+ messages in thread
From: Alex Dubov @ 2011-03-17  3:57 UTC (permalink / raw)
  To: linux-kernel; +Cc: galak, cbouatmailru, mlcreech, linuxppc-dev, davem, netdev

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 alignments of the appropriate FCB. This patch checks
for FCB alignment on such controllers and falls back to software checksumming
if the alignment is known to be bad.

Signed-off-by: Alex Dubov <oakad@yahoo.com>
---
Can we, please, proceed with this patch?
The issue is badly annoying, breaking quite a few of the MPC8548 chips.

Changes for v2:
   - Make indentation slightly more consistent.
   - Replace bizarre switch-based condition with plain boring one.

 drivers/net/gianfar.c |   16 ++++++++++++++--
 drivers/net/gianfar.h |    1 +
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index 5ed8f9f..3da19a5 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))
+		priv->errata |= GFAR_ERRATA_12;
+
 	if (priv->errata)
 		dev_info(dev, "enabled errata workarounds, flags: 0x%x\n",
 			 priv->errata);
@@ -2156,8 +2161,15 @@ 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);
+		/* as specified by errata */
+		if (unlikely(gfar_has_errata(priv, GFAR_ERRATA_12)
+			     && ((unsigned long)fcb % 0x20) > 0x18)) {
+			__skb_pull(skb, GMAC_FCB_LEN);
+			skb_checksum_help(skb);
+		} else {
+			lstatus |= BD_LFLAG(TXBD_TOE);
+			gfar_tx_checksum(skb, fcb);
+		}
 	}
 
 	if (vlan_tx_tag_present(skb)) {
diff --git a/drivers/net/gianfar.h b/drivers/net/gianfar.h
index 54de413..ec5d595 100644
--- a/drivers/net/gianfar.h
+++ b/drivers/net/gianfar.h
@@ -1039,6 +1039,7 @@ enum gfar_errata {
 	GFAR_ERRATA_74		= 0x01,
 	GFAR_ERRATA_76		= 0x02,
 	GFAR_ERRATA_A002	= 0x04,
+	GFAR_ERRATA_12		= 0x08, /* a.k.a errata eTSEC49 */
 };
 
 /* Struct stolen almost completely (and shamelessly) from the FCC enet source
-- 
1.7.3.2




      

^ permalink raw reply related	[flat|nested] 7+ 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   ` Alex Dubov
  0 siblings, 1 reply; 7+ 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] 7+ messages in thread
end of thread, other threads:[~2011-03-18 22:14 UTC | newest]

Thread overview: 7+ 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
2011-03-17  3:57 ` Alex Dubov
2011-03-17  3:57 ` Alex Dubov
2011-03-18 22:15 ` David Miller
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
2011-01-28  4:37   ` Alex Dubov

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.