From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH] marvell sky2 driver: fix so it works without unaligned accesses Date: Tue, 03 Apr 2012 18:18:36 +0200 Message-ID: <1333469916.18626.284.camel@edumazet-glaptop> References: <201204031527.q33FR04i031747@farm-0027.internal.tilera.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Chris Metcalf Return-path: In-Reply-To: <201204031527.q33FR04i031747@farm-0027.internal.tilera.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, 2012-04-03 at 11:13 -0400, Chris Metcalf wrote: > The driver uses a receive_new() routine that ends up requiring unaligned > accesses in IP header processing. If the architecture doesn't support > efficient unaligned accesses, just copy all ingress packets to the bounce > buffers instead. > > This allows the driver to be used on the Tilera TILEmpower-Gx, since > the tile architecture doesn't currently handle kernel unaligned accesses, > just userspace. > > Signed-off-by: Chris Metcalf > --- > drivers/net/ethernet/marvell/sky2.c | 10 +++++++--- > 1 files changed, 7 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/ethernet/marvell/sky2.c b/drivers/net/ethernet/marvell/sky2.c > index 879b0a4..7a15482 100644 > --- a/drivers/net/ethernet/marvell/sky2.c > +++ b/drivers/net/ethernet/marvell/sky2.c > @@ -2490,6 +2490,7 @@ static struct sk_buff *receive_copy(struct sky2_port *sky2, > return skb; > } > > +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS > /* Adjust length of skb with fragments to match received data */ > static void skb_put_frags(struct sk_buff *skb, unsigned int hdr_space, > unsigned int length) > @@ -2555,6 +2556,7 @@ nomap: > nobuf: > return NULL; > } > +#endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */ > > /* > * Receive one packet. > @@ -2598,10 +2600,12 @@ static struct sk_buff *sky2_receive(struct net_device *dev, > goto error; > > okay: > - if (length < copybreak) > - skb = receive_copy(sky2, re, length); > - else > +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS > + if (length >= copybreak) > skb = receive_new(sky2, re, length); > + else > +#endif > + skb = receive_copy(sky2, re, length); > > dev->stats.rx_dropped += (skb == NULL); > The (expensive ?) copy should be done only if (sky2->hw->flags & SKY2_HW_RAM_BUFFER) diff --git a/drivers/net/ethernet/marvell/sky2.c b/drivers/net/ethernet/marvell/sky2.c index b806d9b..3da3cdc 100644 --- a/drivers/net/ethernet/marvell/sky2.c +++ b/drivers/net/ethernet/marvell/sky2.c @@ -2599,7 +2599,11 @@ static struct sk_buff *sky2_receive(struct net_device *dev, goto error; okay: - if (length < copybreak) + if ((length < copybreak) +#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS + || (sky2->hw->flags & SKY2_HW_RAM_BUFFER) +#endif + ) skb = receive_copy(sky2, re, length); else skb = receive_new(sky2, re, length);