Re: [PATCH net-next v2 1/8] ethtool: Add support for configuring frame preemption

On Mon, 18 Jan 2021 16:40:21 -0800 Vinicius Costa Gomes wrote:

+  ====================================  ======  ==========================
+  ``ETHTOOL_A_CHANNELS_HEADER``         nested  request header

ETHTOOL_A_PREEMPT_HEADER

+  ====================================  ======  ==========================
+
+Kernel response contents:
+
+  =====================================  ======  ==========================
+  ``ETHTOOL_A_CHANNELS_HEADER``          nested  reply header

here as well

+  ``ETHTOOL_A_PREEMPT_ENABLED``          u8      frame preemption enabled
+  ``ETHTOOL_A_PREEMPT_ADD_FRAG_SIZE``    u32     Min additional frag size
+  =====================================  ======  ==========================
+
+``ETHTOOL_A_PREEMPT_ADD_FRAG_SIZE`` configures the minimum non-final
+fragment size that the receiver device supports.
+
+PREEMPT_SET
+============
+
+Sets frame preemption parameters.
+
+Request contents:
+
+  =====================================  ======  ==========================
+  ``ETHTOOL_A_CHANNELS_HEADER``          nested  reply header

and here

+  ``ETHTOOL_A_PREEMPT_ENABLED``          u8      frame preemption enabled
+  ``ETHTOOL_A_PREEMPT_ADD_FRAG_SIZE``    u32     Min additional frag size
+  =====================================  ======  ==========================

+struct netlink_ext_ack;

Let's move it all the way to the top, right after header includes, so
we don't have to move it again.

+/**
+ * Convert from a Frame Preemption Additional Fragment size in bytes
+ * to a multiplier. The multiplier is defined as:
+ *	"A 2-bit integer value used to indicate the minimum size of
+ *	non-final fragments supported by the receiver on the given port
+ *	associated with the local System. This value is expressed in units
+ *	of 64 octets of additional fragment length."
+ *	Equivalent to `30.14.1.7 aMACMergeAddFragSize` from the IEEE 802.3-2018
+ *	standard.

Please double check the correct format for kdoc:

https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html

This comment should also be next to the definition of the function, 
not in the header.

+ * @frag_size: minimum non-final fragment size in bytes
+ *
+ * Returns the multiplier.
+ */
+u8 ethtool_frag_size_to_mult(u32 frag_size);