Commit 5fd0f1a0 authored by Russell King (Oracle)'s avatar Russell King (Oracle) Committed by Jakub Kicinski
Browse files

net: phylink: add negotiation of in-band capabilities 



Support for in-band signalling with Serdes links is uncertain. Some
PHYs do not support in-band for e.g. SGMII. Some PCS do not support
in-band for 2500Base-X. Some PCS require in-band for Base-X protocols.

Simply using what is in DT is insufficient when we have hot-pluggable
PHYs e.g. in the form of SFP modules, which may not provide the
in-band signalling.

In order to address this, we have introduced phy_inband_caps() and
pcs_inband_caps() functions to allow phylink to retrieve the
capabilities from each end of the PCS/PHY link. This commit adds code
to resolve whether in-band will be used in the various scenarios that
we have: In-band not being used, PHY present using SGMII or Base-X,
PHY not present. We also deal with no capabilties provided.

Signed-off-by: default avatarRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1tIUsJ-006IUn-H3@rmk-PC.armlinux.org.uk


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent d4169f0c

drivers/net/phy/phylink.c

+144 −10
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ struct phylink { 


	struct mutex state_mutex;

	struct phylink_link_state phy_state;

	unsigned int phy_ib_mode;

	struct work_struct resolve;

	unsigned int pcs_neg_mode;

	unsigned int pcs_state;
@@ -1153,10 +1154,18 @@ static void phylink_pcs_neg_mode(struct phylink *pl, struct phylink_pcs *pcs, 
				 phy_interface_t interface,

				 const unsigned long *advertising)

{

	unsigned int pcs_ib_caps = 0;

	unsigned int phy_ib_caps = 0;

	unsigned int neg_mode, mode;

	enum {

		INBAND_CISCO_SGMII,

		INBAND_BASEX,

	} type;



	mode = pl->req_link_an_mode;



	pl->phy_ib_mode = 0;



	switch (interface) {

	case PHY_INTERFACE_MODE_SGMII:

	case PHY_INTERFACE_MODE_QSGMII:
@@ -1168,10 +1177,7 @@ static void phylink_pcs_neg_mode(struct phylink *pl, struct phylink_pcs *pcs, 
		 * inband communication. Note: there exist PHYs that run

		 * with SGMII but do not send the inband data.

		 */

		if (!phylink_autoneg_inband(mode))

			neg_mode = PHYLINK_PCS_NEG_OUTBAND;

		else

			neg_mode = PHYLINK_PCS_NEG_INBAND_ENABLED;

		type = INBAND_CISCO_SGMII;

		break;



	case PHY_INTERFACE_MODE_1000BASEX:
@@ -1182,18 +1188,139 @@ static void phylink_pcs_neg_mode(struct phylink *pl, struct phylink_pcs *pcs, 
		 * as well, but drivers may not support this, so may

		 * need to override this.

		 */

		if (!phylink_autoneg_inband(mode))

		type = INBAND_BASEX;

		break;



	default:

		pl->pcs_neg_mode = PHYLINK_PCS_NEG_NONE;

		pl->act_link_an_mode = mode;

		return;

	}



	if (pcs)

		pcs_ib_caps = phylink_pcs_inband_caps(pcs, interface);



	if (pl->phydev)

		phy_ib_caps = phy_inband_caps(pl->phydev, interface);



	phylink_dbg(pl, "interface %s inband modes: pcs=%02x phy=%02x\n",

		    phy_modes(interface), pcs_ib_caps, phy_ib_caps);



	if (!phylink_autoneg_inband(mode)) {

		bool pcs_ib_only = false;

		bool phy_ib_only = false;



		if (pcs_ib_caps && pcs_ib_caps != LINK_INBAND_DISABLE) {

			/* PCS supports reporting in-band capabilities, and

			 * supports more than disable mode.

			 */

			if (pcs_ib_caps & LINK_INBAND_DISABLE)

				neg_mode = PHYLINK_PCS_NEG_OUTBAND;

			else if (pcs_ib_caps & LINK_INBAND_ENABLE)

				pcs_ib_only = true;

		}



		if (phy_ib_caps && phy_ib_caps != LINK_INBAND_DISABLE) {

			/* PHY supports in-band capabilities, and supports

			 * more than disable mode.

			 */

			if (phy_ib_caps & LINK_INBAND_DISABLE)

				pl->phy_ib_mode = LINK_INBAND_DISABLE;

			else if (phy_ib_caps & LINK_INBAND_BYPASS)

				pl->phy_ib_mode = LINK_INBAND_BYPASS;

			else if (phy_ib_caps & LINK_INBAND_ENABLE)

				phy_ib_only = true;

		}



		/* If either the PCS or PHY requires inband to be enabled,

		 * this is an invalid configuration. Provide a diagnostic

		 * message for this case, but don't try to force the issue.

		 */

		if (pcs_ib_only || phy_ib_only)

			phylink_warn(pl,

				     "firmware wants %s mode, but %s%s%s requires inband\n",

				     phylink_an_mode_str(mode),

				     pcs_ib_only ? "PCS" : "",

				     pcs_ib_only && phy_ib_only ? " and " : "",

				     phy_ib_only ? "PHY" : "");



		neg_mode = PHYLINK_PCS_NEG_OUTBAND;

	} else if (type == INBAND_CISCO_SGMII || pl->phydev) {

		/* For SGMII modes which are designed to be used with PHYs, or

		 * Base-X with a PHY, we try to use in-band mode where-ever

		 * possible. However, there are some PHYs e.g. BCM84881 which

		 * do not support in-band.

		 */

		const unsigned int inband_ok = LINK_INBAND_ENABLE |

					       LINK_INBAND_BYPASS;

		const unsigned int outband_ok = LINK_INBAND_DISABLE |

						LINK_INBAND_BYPASS;

		/* PCS	PHY

		 * D E	D E

		 * 0 0  0 0	no information			inband enabled

		 * 1 0  0 0	pcs doesn't support		outband

		 * 0 1  0 0	pcs required			inband enabled

		 * 1 1  0 0	pcs optional			inband enabled

		 * 0 0  1 0	phy doesn't support		outband

		 * 1 0  1 0	pcs+phy doesn't support		outband

		 * 0 1  1 0	pcs required, phy doesn't support, invalid

		 * 1 1  1 0	pcs optional, phy doesn't support, outband

		 * 0 0  0 1	phy required			inband enabled

		 * 1 0  0 1	pcs doesn't support, phy required, invalid

		 * 0 1  0 1	pcs+phy required		inband enabled

		 * 1 1  0 1	pcs optional, phy required	inband enabled

		 * 0 0  1 1	phy optional			inband enabled

		 * 1 0  1 1	pcs doesn't support, phy optional, outband

		 * 0 1  1 1	pcs required, phy optional	inband enabled

		 * 1 1  1 1	pcs+phy optional		inband enabled

		 */

		if ((!pcs_ib_caps || pcs_ib_caps & inband_ok) &&

		    (!phy_ib_caps || phy_ib_caps & inband_ok)) {

			/* In-band supported or unknown at both ends. Enable

			 * in-band mode with or without bypass at the PHY.

			 */

			if (phy_ib_caps & LINK_INBAND_ENABLE)

				pl->phy_ib_mode = LINK_INBAND_ENABLE;

			else if (phy_ib_caps & LINK_INBAND_BYPASS)

				pl->phy_ib_mode = LINK_INBAND_BYPASS;



			neg_mode = PHYLINK_PCS_NEG_INBAND_ENABLED;

		} else if ((!pcs_ib_caps || pcs_ib_caps & outband_ok) &&

			   (!phy_ib_caps || phy_ib_caps & outband_ok)) {

			/* Either in-band not supported at at least one end.

			 * In-band bypass at the other end is possible.

			 */

			if (phy_ib_caps & LINK_INBAND_DISABLE)

				pl->phy_ib_mode = LINK_INBAND_DISABLE;

			else if (phy_ib_caps & LINK_INBAND_BYPASS)

				pl->phy_ib_mode = LINK_INBAND_BYPASS;



			neg_mode = PHYLINK_PCS_NEG_OUTBAND;

			if (pl->phydev)

				mode = MLO_AN_PHY;

		} else {

			/* invalid */

			phylink_warn(pl, "%s: incompatible in-band capabilities, trying in-band",

				     phy_modes(interface));

			neg_mode = PHYLINK_PCS_NEG_INBAND_ENABLED;

		}

	} else {

		/* For Base-X without a PHY */

		if (pcs_ib_caps == LINK_INBAND_DISABLE)

			/* If the PCS doesn't support inband, then inband must

			 * be disabled.

			 */

			neg_mode = PHYLINK_PCS_NEG_INBAND_DISABLED;

		else if (pcs_ib_caps == LINK_INBAND_ENABLE)

			/* If the PCS requires inband, then inband must always

			 * be enabled.

			 */

			neg_mode = PHYLINK_PCS_NEG_INBAND_ENABLED;

		else if (linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,

					   advertising))

			neg_mode = PHYLINK_PCS_NEG_INBAND_ENABLED;

		else

			neg_mode = PHYLINK_PCS_NEG_INBAND_DISABLED;

		break;



	default:

		neg_mode = PHYLINK_PCS_NEG_NONE;

		break;

	}



	pl->pcs_neg_mode = neg_mode;
@@ -1292,6 +1419,13 @@ static void phylink_major_config(struct phylink *pl, bool restart, 
				    ERR_PTR(err));

	}



	if (pl->phydev && pl->phy_ib_mode) {

		err = phy_config_inband(pl->phydev, pl->phy_ib_mode);

		if (err < 0)

			phylink_err(pl, "phy_config_inband: %pe\n",

				    ERR_PTR(err));

	}



	if (pl->sfp_bus) {

		rate_kbd = phylink_interface_signal_rate(state->interface);

		if (rate_kbd)