[dpdk-dev] [PATCH V2] doc: add known PHY link up issue for i40e

[Jeff Guo <jia.guo@intel.com>]

If bind i40e NICs with PMD and run application, after application quits,
some kernel driver may not be able to set PHY to link up again by
``ifconfig`` after NICs be rebound to kernel driver.

Signed-off-by: Jeff Guo <jia.guo@intel.com>
---
v2->v1:
refine some typo and word.
---
 doc/guides/rel_notes/known_issues.rst | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/doc/guides/rel_notes/known_issues.rst b/doc/guides/rel_notes/known_issues.rst
index 95e4ce6..f4e3519 100644
--- a/doc/guides/rel_notes/known_issues.rst
+++ b/doc/guides/rel_notes/known_issues.rst
@@ -759,3 +759,30 @@ Netvsc driver and application restart
 
 **Driver/Module**:
    ``uio_hv_generic`` module.
+
+
+PHY link up failed when rebind i40e NICs to kernel driver
+---------------------------------------------------------
+
+**Description**:
+   If bind i40e NICs with PMD and run application, after application quits, some
+   kernel driver may not be able to set PHY to link up again by ``ifconfig``
+   after NICs be rebound to kernel driver.
+
+**Implication**:
+   Before application quits, it will invokes the function ``i40e_dev_stop``,
+   which will set PHY to link down. This is the situation that some kernel
+   driver may not be able to handle link status correctly after it retakes
+   control of the device. It is a known PHY link configure synchronous issue in
+   i40e kernel driver. The fix has been addressed in 2.7.4 rc version. So if
+   the i40e kernel driver is < 2.7.4 and before the fix be backported into the
+   previous versions, it will encounter this issue.
+
+**Resolution/Workaround**:
+   If it does not help by remove and reinsert i40e kernel driver, please reboot system.
+
+**Affected Environment/Platform**:
+   All.
+
+**Driver/Module**:
+   Poll Mode Driver (PMD).
-- 
2.7.4