Merge branch 'net-phylink-fix-pcs-without-autoneg'

Russell King says:

====================
net: phylink: fix PCS without autoneg

Eric Woudstra reported that a PCS attached using 2500base-X does not
see link when phylink is using in-band mode, but autoneg is disabled,
despite there being a valid 2500base-X signal being received. We have
these settings:

	act_link_an_mode = MLO_AN_INBAND
	pcs_neg_mode = PHYLINK_PCS_NEG_INBAND_DISABLED

Eric diagnosed it to phylink_decode_c37_word() setting state->link
false because the full-duplex bit isn't set in the non-existent link
partner advertisement word (which doesn't exist because in-band
autoneg is disabled!)

The test in phylink_mii_c22_pcs_decode_state() is supposed to catch
this state, but since we converted PCS to use neg_mode, testing the
Autoneg in the local advertisement is no longer sufficient - we need
to be looking at the neg_mode, which currently isn't provided.

We need to provide this via the .pcs_get_state() method, and this
will require modifying all PCS implementations to add the extra
argument to this method.

Patch 1 uses the PCS neg_mode in phylink_mac_pcs_get_state() to correct
the now obsolute usage of the Autoneg bit in the advertisement.

Patch 2 passes neg_mode into the .pcs_get_state() method, and updates
all users.

Patch 3 adds neg_mode as an argument to the various clause 22 state
decoder functions in phylink, modifying drivers to pass the neg_mode
through.

Patch 4 makes use of phylink_mii_c22_pcs_decode_state() rather than
using the Autoneg bit in the advertising field.

Patch 5 may be required for Eric's case - it ensures that we report
the correct state for interface types that we support only one set
of modes for when autoneg is disabled.
====================

Link: https://patch.msgid.link/Z4TbR93B-X8A8iHe@shell.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 4b7a20620b49..f19b7108c840 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -446,7 +446,7 @@ struct phylink_pcs_ops {
 			       phy_interface_t interface);
 	int (*pcs_post_config)(struct phylink_pcs *pcs,
 			       phy_interface_t interface);
-	void (*pcs_get_state)(struct phylink_pcs *pcs,
+	void (*pcs_get_state)(struct phylink_pcs *pcs, unsigned int neg_mode,
 			      struct phylink_link_state *state);
 	int (*pcs_config)(struct phylink_pcs *pcs, unsigned int neg_mode,
 			  phy_interface_t interface,
@@ -505,6 +505,7 @@ void pcs_disable(struct phylink_pcs *pcs);
 /**
  * pcs_get_state() - Read the current inband link state from the hardware
  * @pcs: a pointer to a &struct phylink_pcs.
+ * @neg_mode: link negotiation mode (PHYLINK_PCS_NEG_xxx)
  * @state: a pointer to a &struct phylink_link_state.
  *
  * Read the current inband link state from the MAC PCS, reporting the
@@ -513,8 +514,11 @@ void pcs_disable(struct phylink_pcs *pcs);
  * negotiation completion state in @state->an_complete, and link up state
  * in @state->link. If possible, @state->lp_advertising should also be
  * populated.
+ *
+ * Note that the @neg_mode parameter is always the PHYLINK_PCS_NEG_xxx
+ * state, not MLO_AN_xxx.
  */
-void pcs_get_state(struct phylink_pcs *pcs,
+void pcs_get_state(struct phylink_pcs *pcs, unsigned int neg_mode,
 		   struct phylink_link_state *state);
 
 /**
@@ -689,8 +693,9 @@ static inline int phylink_get_link_timer_ns(phy_interface_t interface)
 }
 
 void phylink_mii_c22_pcs_decode_state(struct phylink_link_state *state,
-				      u16 bmsr, u16 lpa);
+				      unsigned int neg_mode, u16 bmsr, u16 lpa);
 void phylink_mii_c22_pcs_get_state(struct mdio_device *pcs,
+				   unsigned int neg_mode,
 				   struct phylink_link_state *state);
 int phylink_mii_c22_pcs_encode_advertisement(phy_interface_t interface,
 					     const unsigned long *advertising);