On Mon, Jun 14, 2010 at 4:32 AM, Lennert Buytenhek
<buytenh@xxxxxxxxxxxxxx> wrote:
> On Sun, Jun 13, 2010 at 10:38:10AM +0300, Saeed Bishara wrote:
>
>> >> >> @@ -2666,6 +2668,9 @@ static int
>> >> >mv643xx_eth_shared_probe(struct platform_device *pdev)
>> >> >> * Detect hardware parameters.
>> >> >> */
>> >> >> msp->t_clk = (pd != NULL && pd->t_clk != 0) ? pd->t_clk
>> >> >: 133000000;
>> >> >> + msp->tx_csum_limit = pd->tx_csum_limit ?
>> >> >pd->tx_csum_limit : 9 * 1024;
>> >> >> + /* add header count so we can compare against skb->len */
>> >> >> + msp->tx_csum_limit += ETH_HLEN;
>> >> >> infer_hw_params(msp);
>> >> >
>> >> >Is the limit 9 * 1024 + 14 for the whole packet, or 9 *
>> >1024 for the IP
>> >> >part?
>> >>
>> >> the limit is for the IP part, but I thought that adding the
>> >header length, then comparing agains skb->len will be the
>> >same. What do you suggest?
>> >
>> >Right, but for the header length you take 14, while if to include VLAN
>> >tags or DSA tags the header might actually be longer -- how does that
>> >affect the ability of the hardware to compute the checksum?
>> >
>> >I.e. is the restriction "total packet length must be < N + 14 bytes"
>> >or is it "the IP part must be < N bytes and it doesn't matter whether
>> >there are VLAN tags or not"?
>>
>> It's the second option: "the IP part must be < N" regardless to the L2 header.
>
> Then I suppose you want to do something like:
>
> int hdr_len;
> int tag_bytes;
>
> hdr_len = (void *)ip_hdr(skb) - (void *)skb->data;
> tag_bytes = hdr_len - 4;
that should be 14 instead of 4, right?
> if (skb->len - hdr_len > the limit || unlikely(tag_bytes & ~12)) {
>
> (And then keep the limit as maximum number of bytes in the packet
> starting from the IP header part.)
ok. here is the updated patch:
>From 009530d4220dd710737d5a357629edcbc102727a Mon Sep 17 00:00:00 2001
From: Saeed Bishara <saeed@xxxxxxxxxxx>
Date: Sun, 6 Jun 2010 14:40:49 +0300
Subject: [PATCH 1/2 v3] mv643xx_eth: use sw csum for big packets
Some controllers (KW, Dove) limits the TX IP/layer4 checksum
offloading to a max size.
Signed-off-by: Saeed Bishara <saeed@xxxxxxxxxxx>
---
drivers/net/mv643xx_eth.c | 9 +++++++--
include/linux/mv643xx_eth.h | 5 +++++
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index e345ec8..73bb8ea 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -289,6 +289,7 @@ struct mv643xx_eth_shared_private {
unsigned int t_clk;
int extended_rx_coal_limit;
int tx_bw_control;
+ int tx_csum_limit;
};
#define TX_BW_CONTROL_ABSENT 0
@@ -776,13 +777,16 @@ static int txq_submit_skb(struct tx_queue *txq,
struct sk_buff *skb)
l4i_chk = 0;
if (skb->ip_summed == CHECKSUM_PARTIAL) {
+ int hdr_len;
int tag_bytes;
BUG_ON(skb->protocol != htons(ETH_P_IP) &&
skb->protocol != htons(ETH_P_8021Q));
- tag_bytes = (void *)ip_hdr(skb) - (void *)skb->data - ETH_HLEN;
- if (unlikely(tag_bytes & ~12)) {
+ hdr_len = (void *)ip_hdr(skb) - (void *)skb->data;
+ tag_bytes = hdr_len - ETH_HLEN;
+ if (skb->len - hdr_len > mp->shared->tx_csum_limit ||
+ unlikely(tag_bytes & ~12)) {
if (skb_checksum_help(skb) == 0)
goto no_csum;
kfree_skb(skb);
@@ -2666,6 +2670,7 @@ static int mv643xx_eth_shared_probe(struct
platform_device *pdev)
* Detect hardware parameters.
*/
msp->t_clk = (pd != NULL && pd->t_clk != 0) ? pd->t_clk : 133000000;
+ msp->tx_csum_limit = pd->tx_csum_limit ? pd->tx_csum_limit : 9 * 1024;
infer_hw_params(msp);
platform_set_drvdata(pdev, msp);
diff --git a/include/linux/mv643xx_eth.h b/include/linux/mv643xx_eth.h
index cbbbe9b..30b0c4e 100644
--- a/include/linux/mv643xx_eth.h
+++ b/include/linux/mv643xx_eth.h
@@ -19,6 +19,11 @@ struct mv643xx_eth_shared_platform_data {
struct mbus_dram_target_info *dram;
struct platform_device *shared_smi;
unsigned int t_clk;
+ /*
+ * Max packet size for Tx IP/Layer 4 checksum, when set to 0, default
+ * limit of 9KiB will be used.
+ */
+ int tx_csum_limit;
};
#define MV643XX_ETH_PHY_ADDR_DEFAULT 0
--
1.6.0.4
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