[PATCH v5 4/4] doc: announce TxPP support for E830 adapters

[Soumyadeep Hore]

E830 adapters currently support Tx Time based queues.

Signed-off-by: Soumyadeep Hore <soumyadeep.hore at intel.com>
---
 doc/guides/nics/ice.rst | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/doc/guides/nics/ice.rst b/doc/guides/nics/ice.rst
index 77985ae5a2..e7d1fb2e1b 100644
--- a/doc/guides/nics/ice.rst
+++ b/doc/guides/nics/ice.rst
@@ -415,6 +415,31 @@ and add the ``--force-max-simd-bitwidth=64`` startup parameter to disable vector
 
    examples/dpdk-ptpclient -c f -n 3 -a 0000:ec:00.1 --force-max-simd-bitwidth=64 -- -T 1 -p 0x1 -c 1
 
+Tx Packet Pacing
+~~~~~~~~~~~~~~~~
+
+In order to deliver the timestamp with every packet, a special type of Tx Host Queue is
+used, the TS Queue. This feature is currently supported only in E830 adapters.
+
+The tx_offload ``RTE_ETH_TX_OFFLOAD_SEND_ON_TIMESTAMP`` is used to enable the feature.
+In order to deliver timestamps internally ``set txtimes`` is used where inter burst
+and intra burst time interval in nsecs is provided.
+For example:
+
+.. code-block:: console
+
+   dpdk-testpmd -a 0000:31:00.0 -c f -n 4 -- -i --tx-offloads=0x200000
+   set fwd txonly
+   set txtimes <inter_burst>,<intra_burst>
+   start
+
+Based on the offload Tx Time Queue will be enabled during ice_tx_queue_setup()
+only for E830 adapters. The initial time should be fetched using
+rte_eth_read_clock(). Further the timestamps should be calculated based on the
+inter_burst and intra_burst times, then storing it into proper format as to be
+placed in packet header. The timestamps should then be copied to packet mbufs
+and packet header length should be adjusted accordingly.
+
 Generic Flow Support
 ~~~~~~~~~~~~~~~~~~~~
 
-- 
2.43.0