[PATCH v2 net-next] ethtool: link 10000baseCR to SFF-8431, Appendix-E SFP+ DA

[Siddaraju DH <siddaraju.dh@intel.com>]

Add comment to clarify the physical media 10000baseCR follows.

10000baseCR does not correspond to any IEEE 802.3 *base-CR PMD.
It has no autonegotiation, no link training, and no mandatory FEC.
The industry standard for this media type is SFF-8431 Appendix-E
Direct Attach cable, also known as 10G_SFI_DA.

Link: https://lore.kernel.org/r/SN7PR11MB69003D33489DB1D6B17EF72A9AF52@SN7PR11MB6900.namprd11.prod.outlook.com

Signed-off-by: Siddaraju DH <siddaraju.dh@intel.com>
---
 include/uapi/linux/ethtool.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index a2091d4e00f3..986d70caec33 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -2013,7 +2013,13 @@ enum ethtool_link_mode_bit_indices {
 	ETHTOOL_LINK_MODE_100000baseLR4_ER4_Full_BIT	= 39,
 	ETHTOOL_LINK_MODE_50000baseSR2_Full_BIT		= 40,
 	ETHTOOL_LINK_MODE_1000baseX_Full_BIT	= 41,
+
+	/* Despite the "baseCR" in 10000baseCR, this is not an IEEE 802.3 baseCR
+	 * It represents SFF-8431 Appendix-E SFP+ Direct Attach (10G-SFI-DA).
+	 * The name is kept as-is for uAPI backward compatibility.
+	 */
 	ETHTOOL_LINK_MODE_10000baseCR_Full_BIT	= 42,
+
 	ETHTOOL_LINK_MODE_10000baseSR_Full_BIT	= 43,
 	ETHTOOL_LINK_MODE_10000baseLR_Full_BIT	= 44,
 	ETHTOOL_LINK_MODE_10000baseLRM_Full_BIT	= 45,
-- 
2.25.1