On 05/08/2020 00:07, Russell King - ARM Linux admin wrote:

On Tue, Aug 04, 2020 at 11:56:12PM +0300, Grygorii Strashko wrote:

quoted

On 31/07/2020 13:06, Kurt Kanzenbach wrote:

quoted

On Thu Jul 30 2020, Petr Machata wrote:

quoted

Kurt Kanzenbach [off-list ref] writes:

quoted

@@ -107,6 +107,37 @@ unsigned int ptp_classify_raw(const struct sk_buff *skb)
   }
   EXPORT_SYMBOL_GPL(ptp_classify_raw);
+struct ptp_header *ptp_parse_header(struct sk_buff *skb, unsigned int type)
+{
+	u8 *data = skb_mac_header(skb);
+	u8 *ptr = data;

One of the "data" and "ptr" variables is superfluous.

Yeah. Can be shortened to u8 *ptr = skb_mac_header(skb);

Actually usage of skb_mac_header(skb) breaks CPTS RX time-stamping on
am571x platform PATCH 6.

The CPSW RX timestamp requested after full packet put in SKB, but
before calling eth_type_trans().

So, skb->data pints on Eth header, but skb_mac_header() return garbage.

Below diff fixes it for me.

However, that's likely to break everyone else.

For example, anyone calling this from the mii_timestamper rxtstamp()
method, the skb will have been classified with the MAC header pushed
and restored, so skb->data points at the network header.

Your change means that ptp_parse_header() expects the MAC header to
also be pushed.

Is it possible to adjust CPTS?

Looking at:
drivers/net/ethernet/ti/cpsw.c... yes.
drivers/net/ethernet/ti/cpsw_new.c... yes.
drivers/net/ethernet/ti/netcp_core.c... unclear.

If not, maybe cpts should remain unconverted - I don't see any reason
to provide a generic function for one user.

Could it be an option to pass "u8 *ptr" instead of "const struct sk_buff *skb" as
input parameter to ptp_parse_header()?

-- 
Best regards,
grygorii