patch 'doc: describe timestamp limitations for mlx5' has been queued to stable release 19.11.11

[christian.ehrhardt at canonical.com]

Hi,

FYI, your patch has been queued to stable release 19.11.11

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before December 10th 2021. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/cpaelzer/dpdk-stable-queue

This queued commit can be viewed at:
https://github.com/cpaelzer/dpdk-stable-queue/commit/df4b9cae885a3da71b437fbb5f67c8da10a10dc1

Thanks.

Christian Ehrhardt <christian.ehrhardt at canonical.com>

---
>From df4b9cae885a3da71b437fbb5f67c8da10a10dc1 Mon Sep 17 00:00:00 2001
From: Viacheslav Ovsiienko <viacheslavo at nvidia.com>
Date: Mon, 8 Nov 2021 18:41:01 +0200
Subject: [PATCH] doc: describe timestamp limitations for mlx5

[ upstream commit 1a3709c1f021afbe58db4a27a179127e561fe401 ]

The ConnectX NIC series hardware provides only 63-bit
wide timestamps. The imposed limitations description
added to documentation.

At the moment there are no affected applications known
or bug reports neither, this is just the declaration
of limitation.

Signed-off-by: Viacheslav Ovsiienko <viacheslavo at nvidia.com>
---
 doc/guides/nics/mlx5.rst | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index e81875de50..6deea36537 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -227,6 +227,20 @@ Limitations
   - Rx queue with LRO offload enabled, receiving a non-LRO packet, can forward
     it with size limited to max LRO size, not to max RX packet length.
 
+- Timestamps:
+
+  - CQE timestamp field width is limited by hardware to 63 bits, MSB is zero.
+  - In the free-running mode the timestamp counter is reset on power on
+    and 63-bit value provides over 1800 years of uptime till overflow.
+  - In the real-time mode
+    (configurable with ``REAL_TIME_CLOCK_ENABLE`` firmware settings),
+    the timestamp presents the nanoseconds elapsed since 01-Jan-1970,
+    hardware timestamp overflow will happen on 19-Jan-2038
+    (0x80000000 seconds since 01-Jan-1970).
+  - The send scheduling is based on timestamps
+    from the reference "Clock Queue" completions,
+    the scheduled send timestamps should not be specified with non-zero MSB.
+
 Statistics
 ----------
 
@@ -839,6 +853,10 @@ Below are some firmware configurations listed.
 
    FLEX_PARSER_PROFILE_ENABLE=0
 
+- enable realtime timestamp format::
+
+   REAL_TIME_CLOCK_ENABLE=1
+
 Prerequisites
 -------------
 
-- 
2.34.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2021-11-30 16:50:13.533034998 +0100
+++ 0131-doc-describe-timestamp-limitations-for-mlx5.patch	2021-11-30 16:50:05.966874821 +0100
@@ -1 +1 @@
-From 1a3709c1f021afbe58db4a27a179127e561fe401 Mon Sep 17 00:00:00 2001
+From df4b9cae885a3da71b437fbb5f67c8da10a10dc1 Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 1a3709c1f021afbe58db4a27a179127e561fe401 ]
+
@@ -14,2 +15,0 @@
-Cc: stable at dpdk.org
-
@@ -22 +22 @@
-index d175c2061e..552e06c0db 100644
+index e81875de50..6deea36537 100644
@@ -25,3 +25,3 @@
-@@ -480,6 +480,20 @@ Limitations
- 
-   - Needs OFED 5.4+.
+@@ -227,6 +227,20 @@ Limitations
+   - Rx queue with LRO offload enabled, receiving a non-LRO packet, can forward
+     it with size limited to max LRO size, not to max RX packet length.
@@ -46,3 +46,3 @@
-@@ -1242,6 +1256,10 @@ Below are some firmware configurations listed.
-    FLEX_PARSER_PROFILE_ENABLE=4
-    PROG_PARSE_GRAPH=1
+@@ -839,6 +853,10 @@ Below are some firmware configurations listed.
+ 
+    FLEX_PARSER_PROFILE_ENABLE=0
@@ -54,2 +54,2 @@
- Linux Prerequisites
- -------------------
+ Prerequisites
+ -------------