[PATCH net-next] net: phylink: expand on .pcs_config() method documentation

["Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>]

Expand on the requirements of the .pcs_config() method documentation,
specifically mentioning that it should cause minimal disruption to
an established link, and that it should return a positive non-zero
value when requiring the .pcs_an_restart() method to be called.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 include/linux/phylink.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index c187267a15b6..79876c84ae81 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -595,6 +595,14 @@ void pcs_get_state(struct phylink_pcs *pcs, unsigned int neg_mode,
  * The %neg_mode argument should be tested via the phylink_mode_*() family of
  * functions, or for PCS that set pcs->neg_mode true, should be tested
  * against the PHYLINK_PCS_NEG_* definitions.
+ *
+ * pcs_config() will be called when configuration of the PCS is required
+ * or when the advertisement is possibly updated. It must not unnecessarily
+ * disrupt an established link.
+ *
+ * When an autonegotiation restart is required for 802.3z modes, .pcs_config()
+ * should return a positive non-zero integer (e.g. 1) to indicate to phylink
+ * to call the pcs_an_restart() method.
  */
 int pcs_config(struct phylink_pcs *pcs, unsigned int neg_mode,
 	       phy_interface_t interface, const unsigned long *advertising,
-- 
2.30.2