* [PATCH 1/1] AX88179_178A: Add FLAG_HW_IPALIGN to determine whether reserving NET_IP_ALIGN bytes for an SKB.
@ 2013-12-13 9:25 freddy
[not found] ` <1386926708-2343-1-git-send-email-freddy-knRN6Y/kmf1NUHwG+Fw1Kw@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: freddy @ 2013-12-13 9:25 UTC (permalink / raw)
To: netdev, davem, linux-usb, linux-kernel, louis, allan; +Cc: Freddy Xin
From: Freddy Xin <freddy@asix•com.tw>
The AX88179_178A has a hardware feature that it can insert a
2-bytes pseudo header in front of each received frame by setting
the AX_RX_CTL_IPE bit. This feature is used to let the IP header
be aligned on a doubleword-aligned address, so the rx_submit() of
usbnet.c needn't reserve NET_IP_ALIGN bytes for an SKB in the case.
This patch adds a flag of driver_info "FLAG_HW_IPALIGN" which is
used in rx_submit() of usbnet.c to determine whether reserving
NET_IP_ALIGN bytes for an SKB.
Signed-off-by: Freddy Xin <freddy@asix•com.tw>
---
drivers/net/usb/ax88179_178a.c | 8 ++++----
drivers/net/usb/usbnet.c | 5 ++++-
include/linux/usb/usbnet.h | 3 +++
3 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/net/usb/ax88179_178a.c b/drivers/net/usb/ax88179_178a.c
index 8e8d0fc..04a2cc9 100644
--- a/drivers/net/usb/ax88179_178a.c
+++ b/drivers/net/usb/ax88179_178a.c
@@ -1374,7 +1374,7 @@ static const struct driver_info ax88179_info = {
.link_reset = ax88179_link_reset,
.reset = ax88179_reset,
.stop = ax88179_stop,
- .flags = FLAG_ETHER | FLAG_FRAMING_AX,
+ .flags = FLAG_ETHER | FLAG_FRAMING_AX | FLAG_HW_IPALIGN,
.rx_fixup = ax88179_rx_fixup,
.tx_fixup = ax88179_tx_fixup,
};
@@ -1387,7 +1387,7 @@ static const struct driver_info ax88178a_info = {
.link_reset = ax88179_link_reset,
.reset = ax88179_reset,
.stop = ax88179_stop,
- .flags = FLAG_ETHER | FLAG_FRAMING_AX,
+ .flags = FLAG_ETHER | FLAG_FRAMING_AX | FLAG_HW_IPALIGN,
.rx_fixup = ax88179_rx_fixup,
.tx_fixup = ax88179_tx_fixup,
};
@@ -1400,7 +1400,7 @@ static const struct driver_info sitecom_info = {
.link_reset = ax88179_link_reset,
.reset = ax88179_reset,
.stop = ax88179_stop,
- .flags = FLAG_ETHER | FLAG_FRAMING_AX,
+ .flags = FLAG_ETHER | FLAG_FRAMING_AX | FLAG_HW_IPALIGN,
.rx_fixup = ax88179_rx_fixup,
.tx_fixup = ax88179_tx_fixup,
};
@@ -1413,7 +1413,7 @@ static const struct driver_info samsung_info = {
.link_reset = ax88179_link_reset,
.reset = ax88179_reset,
.stop = ax88179_stop,
- .flags = FLAG_ETHER | FLAG_FRAMING_AX,
+ .flags = FLAG_ETHER | FLAG_FRAMING_AX | FLAG_HW_IPALIGN,
.rx_fixup = ax88179_rx_fixup,
.tx_fixup = ax88179_tx_fixup,
};
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 8494bb5..8a618b8 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -473,7 +473,10 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
return -ENOLINK;
}
- skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
+ if (dev->driver_info->flags & FLAG_HW_IPALIGN)
+ skb = __netdev_alloc_skb(dev->net, size, flags);
+ else
+ skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
if (!skb) {
netif_dbg(dev, rx_err, dev->net, "no rx skb\n");
usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
index e303eef..e4855cf 100644
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -116,6 +116,9 @@ struct driver_info {
#define FLAG_MULTI_PACKET 0x2000
#define FLAG_RX_ASSEMBLE 0x4000 /* rx packets may span >1 frames */
#define FLAG_NOARP 0x8000 /* device can't do ARP */
+#define FLAG_HW_IPALIGN 0x10000 /* hardware adds headers to let the
+ * IP header align on a dword-aligned
+ * address */
/* init device ... can sleep, or cause probe() failure */
int (*bind)(struct usbnet *, struct usb_interface *);
--
1.8.3.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* RE: [PATCH 1/1] AX88179_178A: Add FLAG_HW_IPALIGN to determine whether reserving NET_IP_ALIGN bytes for an SKB.
[not found] ` <1386926708-2343-1-git-send-email-freddy-knRN6Y/kmf1NUHwG+Fw1Kw@public.gmane.org>
@ 2013-12-13 10:36 ` David Laight
2013-12-16 6:54 ` Freddy Xin
0 siblings, 1 reply; 6+ messages in thread
From: David Laight @ 2013-12-13 10:36 UTC (permalink / raw)
To: freddy-knRN6Y/kmf1NUHwG+Fw1Kw, netdev-u79uwXL29TY76Z2rM5mHXA,
davem-fT/PcQaiUtIeIZ0/mPfg9Q, linux-usb-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, louis-knRN6Y/kmf1NUHwG+Fw1Kw,
allan-knRN6Y/kmf1NUHwG+Fw1Kw
> From: freddy-knRN6Y/kmf1NUHwG+Fw1Kw@public•gmane.org
...
> - skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
> + if (dev->driver_info->flags & FLAG_HW_IPALIGN)
> + skb = __netdev_alloc_skb(dev->net, size, flags);
> + else
> + skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
Given the definition:
static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
unsigned int length, gfp_t gfp)
{
struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
if (NET_IP_ALIGN && skb)
skb_reserve(skb, NET_IP_ALIGN);
return skb;
}
It really ought to be possible to code that without an extra conditional.
David
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] AX88179_178A: Add FLAG_HW_IPALIGN to determine whether reserving NET_IP_ALIGN bytes for an SKB.
2013-12-13 10:36 ` David Laight
@ 2013-12-16 6:54 ` Freddy Xin
[not found] ` <52AEA3A8.2020906-knRN6Y/kmf1NUHwG+Fw1Kw@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: Freddy Xin @ 2013-12-16 6:54 UTC (permalink / raw)
To: David Laight, netdev, davem, linux-usb, linux-kernel, louis,
allan
On 2013年12月13日 18:36, David Laight wrote:
>> From: freddy@asix•com.tw
> ...
>> - skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
>> + if (dev->driver_info->flags & FLAG_HW_IPALIGN)
>> + skb = __netdev_alloc_skb(dev->net, size, flags);
>> + else
>> + skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
> Given the definition:
> static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
> unsigned int length, gfp_t gfp)
> {
> struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
>
> if (NET_IP_ALIGN && skb)
> skb_reserve(skb, NET_IP_ALIGN);
> return skb;
> }
>
> It really ought to be possible to code that without an extra conditional.
>
> David
>
>
>
>
The AX88179_178A driver do need to know the value of NET_IP_ALIGN
to determine whether enabling the feature that makes IP header align
on a dword-aligned address, but according to the comments from David
Miller, I need to consider all situations, not just for the case that
NET_IP_ALIGN is zero, so the condition added in rx_submit is just used to
determine whether reserving NET_IP_ALIGN bytes for each SKB.
Freddy
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [PATCH 1/1] AX88179_178A: Add FLAG_HW_IPALIGN to determine whether reserving NET_IP_ALIGN bytes for an SKB.
[not found] ` <52AEA3A8.2020906-knRN6Y/kmf1NUHwG+Fw1Kw@public.gmane.org>
@ 2013-12-16 10:09 ` David Laight
2013-12-19 3:14 ` Freddy Xin
0 siblings, 1 reply; 6+ messages in thread
From: David Laight @ 2013-12-16 10:09 UTC (permalink / raw)
To: Freddy Xin, netdev-u79uwXL29TY76Z2rM5mHXA,
davem-fT/PcQaiUtIeIZ0/mPfg9Q, linux-usb-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, louis-knRN6Y/kmf1NUHwG+Fw1Kw,
allan-knRN6Y/kmf1NUHwG+Fw1Kw
> From: Freddy Xin
> On 2013年12月13日 18:36, David Laight wrote:
> >> From: freddy@asix•com.tw
> > ...
> >> - skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
> >> + if (dev->driver_info->flags & FLAG_HW_IPALIGN)
> >> + skb = __netdev_alloc_skb(dev->net, size, flags);
> >> + else
> >> + skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
> > Given the definition:
> > static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
> > unsigned int length, gfp_t gfp)
> > {
> > struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
> >
> > if (NET_IP_ALIGN && skb)
> > skb_reserve(skb, NET_IP_ALIGN);
> > return skb;
> > }
> >
> > It really ought to be possible to code that without an extra conditional.
> >
> > David
>
> The AX88179_178A driver do need to know the value of NET_IP_ALIGN
> to determine whether enabling the feature that makes IP header align
> on a dword-aligned address, but according to the comments from David
> Miller, I need to consider all situations, not just for the case that
> NET_IP_ALIGN is zero, so the condition added in rx_submit is just used to
> determine whether reserving NET_IP_ALIGN bytes for each SKB.
I was thinking of something like:
skb = netdev_alloc_skb(dev, length + dev->skb_align, gfp);
if (NET_IP_ALIGN && skb && !(ev->driver_flags & FLAG_HW_IPALIGN))
skb_reserve(skb, NET_IP_ALIGN);
It might even be reasonable to remove the length adjustment - provided
that all the later code uses the skb length.
David
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] AX88179_178A: Add FLAG_HW_IPALIGN to determine whether reserving NET_IP_ALIGN bytes for an SKB.
2013-12-16 10:09 ` David Laight
@ 2013-12-19 3:14 ` Freddy Xin
2013-12-19 10:01 ` David Laight
0 siblings, 1 reply; 6+ messages in thread
From: Freddy Xin @ 2013-12-19 3:14 UTC (permalink / raw)
To: David Laight, netdev, davem, linux-usb, linux-kernel, louis,
allan
On 2013年12月16日 18:09, David Laight wrote:
>> I was thinking of something like: skb = netdev_alloc_skb(dev, length
>> + dev->skb_align, gfp); if (NET_IP_ALIGN && skb && !(ev->driver_flags
>> & FLAG_HW_IPALIGN)) skb_reserve(skb, NET_IP_ALIGN); It might even be
>> reasonable to remove the length adjustment - provided that all the
>> later code uses the skb length. David
Thanks for your advice.
In the way you advised, does the dev->skb_align equal
to NET_IP_ALIGN in the case that HW doesn't supoort
IP alignment?
In other words, dev->skb_align should be initialized to
NET_IP_ALIGN in USBNET, and I can change its value to
0 in AX88179_178A driver, right?
Freddy
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [PATCH 1/1] AX88179_178A: Add FLAG_HW_IPALIGN to determine whether reserving NET_IP_ALIGN bytes for an SKB.
2013-12-19 3:14 ` Freddy Xin
@ 2013-12-19 10:01 ` David Laight
0 siblings, 0 replies; 6+ messages in thread
From: David Laight @ 2013-12-19 10:01 UTC (permalink / raw)
To: Freddy Xin, netdev, davem, linux-usb, linux-kernel, louis, allan
> From: Freddy Xin
> On 2013年12月16日 18:09, David Laight wrote:
> >> I was thinking of something like: skb = netdev_alloc_skb(dev, length
> >> + dev->skb_align, gfp); if (NET_IP_ALIGN && skb && !(ev->driver_flags
> >> & FLAG_HW_IPALIGN)) skb_reserve(skb, NET_IP_ALIGN); It might even be
> >> reasonable to remove the length adjustment - provided that all the
> >> later code uses the skb length. David
>
> Thanks for your advice.
> In the way you advised, does the dev->skb_align equal
> to NET_IP_ALIGN in the case that HW doesn't supoort
> IP alignment?
Yes
> In other words, dev->skb_align should be initialized to
> NET_IP_ALIGN in USBNET, and I can change its value to
> 0 in AX88179_178A driver, right?
I'd probably set a flag to request that usbnet set the offset
to the correct value. That makes the initialisation a bit clearer.
David
^ permalink raw reply [flat|nested] 6+ messages in thread
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2013-12-13 9:25 [PATCH 1/1] AX88179_178A: Add FLAG_HW_IPALIGN to determine whether reserving NET_IP_ALIGN bytes for an SKB freddy
[not found] ` <1386926708-2343-1-git-send-email-freddy-knRN6Y/kmf1NUHwG+Fw1Kw@public.gmane.org>
2013-12-13 10:36 ` David Laight
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2013-12-19 10:01 ` David Laight
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