[PATCH v3 1/2] net: macb: Allow SGMII only if we are a GEM in mac_validate

This aligns mac_validate with mac_config. In mac_config, SGMII is only
enabled if macb_is_gem. Validate should care if the mac is a gem as
well.

Fixes: 7897b071ac3b ("net: macb: convert to phylink")
Signed-off-by: Sean Anderson <redacted>
---

Changes in v3:
- Order bugfix patch first

Changes in v2:
- New

 drivers/net/ethernet/cadence/macb_main.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 683f14665c2c..cb0f86544955 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c

@@ -528,6 +528,7 @@ static void macb_validate(struct phylink_config *config,
 
 	if (!macb_is_gem(bp) &&
 	    (state->interface == PHY_INTERFACE_MODE_GMII ||
+	     state->interface == PHY_INTERFACE_MODE_SGMII ||
 	     phy_interface_mode_is_rgmii(state->interface))) {
 		bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
 		return;

-- 
2.25.1

As the number of interfaces grows, the number of if statements grows
ever more unweildy. Clean everything up a bit by using a switch
statement. This reduces the number of if statements, and the number of
times the same condition is checked. No functional change intended.

Signed-off-by: Sean Anderson <redacted>
---
This patch was originally submitted as [1].

There is another approach which could be used here. We could do
something like

macb_set_mode(bp, mask, iface)
{
        switch (iface) {
        case 10GBASER:
                if (...)
                        phylink_set_10g_modes(mask);
                else
                        return -EINVAL;
                break;
        case GMII:
        /* etc etc */
        }
        return 0;
}

macb_validate(...)
{
        if (state->interface == PHY_INTERFACE_MODE_NA) {
                macb_set_mode(bp, mask, PHY_INTERFACE_MODE_10GBASER);
                macb_set_mode(bp, mask, PHY_INTERFACE_MODE_GMII);
                macb_set_mode(bp, mask, PHY_INTERFACE_MODE_MII);
        } else if (macb_set_mode(bp, mask, state->interface)) {
                bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
                return;
        }

        /* etc etc */
}

which has the advantage of much cleaner logic in the switch statement.

[1] https://lore.kernel.org/netdev/20211004191527.1610759-9-sean.anderson@seco.com/

Changes in v3:
- Remove labels/gotos in favor of explicit zeroing. Hopefully this
  better illustrates the "linear" flow of the logic.
- Add comment with overview of the flow of the logic.

Changes in v2:
- Fix polarity of `one` being inverted
- Only set gigabit modes for NA if macb_is_gem()

 drivers/net/ethernet/cadence/macb_main.c | 105 ++++++++++++-----------
 1 file changed, 55 insertions(+), 50 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index cb0f86544955..9b2173c37edb 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c

@@ -510,33 +510,65 @@ static void macb_validate(struct phylink_config *config,
 			  unsigned long *supported,
 			  struct phylink_link_state *state)
 {
+	bool one = state->interface != PHY_INTERFACE_MODE_NA;
 	struct net_device *ndev = to_net_dev(config->dev);
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };
 	struct macb *bp = netdev_priv(ndev);
 
-	/* We only support MII, RMII, GMII, RGMII & SGMII. */
-	if (state->interface != PHY_INTERFACE_MODE_NA &&
-	    state->interface != PHY_INTERFACE_MODE_MII &&
-	    state->interface != PHY_INTERFACE_MODE_RMII &&
-	    state->interface != PHY_INTERFACE_MODE_GMII &&
-	    state->interface != PHY_INTERFACE_MODE_SGMII &&
-	    state->interface != PHY_INTERFACE_MODE_10GBASER &&
-	    !phy_interface_mode_is_rgmii(state->interface)) {
-		bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
-		return;
-	}
-
-	if (!macb_is_gem(bp) &&
-	    (state->interface == PHY_INTERFACE_MODE_GMII ||
-	     state->interface == PHY_INTERFACE_MODE_SGMII ||
-	     phy_interface_mode_is_rgmii(state->interface))) {
-		bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
-		return;
-	}
-
-	if (state->interface == PHY_INTERFACE_MODE_10GBASER &&
-	    !(bp->caps & MACB_CAPS_HIGH_SPEED &&
-	      bp->caps & MACB_CAPS_PCS)) {
+	/* There are three major types of interfaces we support:
+	 * - (R)MII supporting 10/100 Mbit/s
+	 * - GMII, RGMII, and SGMII supporting 10/100/1000 Mbit/s
+	 * - 10GBASER supporting 10 Gbit/s only
+	 * Because GMII and MII both support 10/100, GMII falls through to MII.
+	 *
+	 * If we can't support an interface mode, we just clear the supported
+	 * mask and return. The major complication is that if we get
+	 * PHY_INTERFACE_MODE_NA, we must return all modes we support.  Because
+	 * of this, NA starts at the top of the switch and falls all the way to
+	 * the bottom, and doesn't return early if we don't support a
+	 * particular mode.
+	 */
+	switch (state->interface) {
+	case PHY_INTERFACE_MODE_NA:
+	case PHY_INTERFACE_MODE_10GBASER:
+		if (bp->caps & MACB_CAPS_HIGH_SPEED &&
+		    bp->caps & MACB_CAPS_PCS &&
+		    bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE) {
+			phylink_set_10g_modes(mask);
+			phylink_set(mask, 10000baseKR_Full);
+		} else if (one) {
+			bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
+			return;
+		}
+		if (one)
+			break;
+		fallthrough;
+	case PHY_INTERFACE_MODE_GMII:
+	case PHY_INTERFACE_MODE_RGMII:
+	case PHY_INTERFACE_MODE_RGMII_ID:
+	case PHY_INTERFACE_MODE_RGMII_RXID:
+	case PHY_INTERFACE_MODE_RGMII_TXID:
+	case PHY_INTERFACE_MODE_SGMII:
+		if (macb_is_gem(bp)) {
+			if (bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE) {
+				phylink_set(mask, 1000baseT_Full);
+				phylink_set(mask, 1000baseX_Full);
+				if (!(bp->caps & MACB_CAPS_NO_GIGABIT_HALF))
+					phylink_set(mask, 1000baseT_Half);
+			}
+		} else if (one) {
+			bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
+			return;
+		}
+		fallthrough;
+	case PHY_INTERFACE_MODE_MII:
+	case PHY_INTERFACE_MODE_RMII:
+		phylink_set(mask, 10baseT_Half);
+		phylink_set(mask, 10baseT_Full);
+		phylink_set(mask, 100baseT_Half);
+		phylink_set(mask, 100baseT_Full);
+		break;
+	default:
 		bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
 		return;
 	}

@@ -544,33 +576,6 @@ static void macb_validate(struct phylink_config *config,
 	phylink_set_port_modes(mask);
 	phylink_set(mask, Autoneg);
 	phylink_set(mask, Asym_Pause);
-
-	if (bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE &&
-	    (state->interface == PHY_INTERFACE_MODE_NA ||
-	     state->interface == PHY_INTERFACE_MODE_10GBASER)) {
-		phylink_set_10g_modes(mask);
-		phylink_set(mask, 10000baseKR_Full);
-		if (state->interface != PHY_INTERFACE_MODE_NA)
-			goto out;
-	}
-
-	phylink_set(mask, 10baseT_Half);
-	phylink_set(mask, 10baseT_Full);
-	phylink_set(mask, 100baseT_Half);
-	phylink_set(mask, 100baseT_Full);
-
-	if (bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE &&
-	    (state->interface == PHY_INTERFACE_MODE_NA ||
-	     state->interface == PHY_INTERFACE_MODE_GMII ||
-	     state->interface == PHY_INTERFACE_MODE_SGMII ||
-	     phy_interface_mode_is_rgmii(state->interface))) {
-		phylink_set(mask, 1000baseT_Full);
-		phylink_set(mask, 1000baseX_Full);
-
-		if (!(bp->caps & MACB_CAPS_NO_GIGABIT_HALF))
-			phylink_set(mask, 1000baseT_Half);
-	}
-out:
 	bitmap_and(supported, supported, mask, __ETHTOOL_LINK_MODE_MASK_NBITS);
 	bitmap_and(state->advertising, state->advertising, mask,
 		   __ETHTOOL_LINK_MODE_MASK_NBITS);

-- 
2.25.1

Quoting Sean Anderson (2021-10-12 21:46:44)

+       /* There are three major types of interfaces we support:
+        * - (R)MII supporting 10/100 Mbit/s
+        * - GMII, RGMII, and SGMII supporting 10/100/1000 Mbit/s
+        * - 10GBASER supporting 10 Gbit/s only
+        * Because GMII and MII both support 10/100, GMII falls through to MII.
+        *
+        * If we can't support an interface mode, we just clear the supported
+        * mask and return. The major complication is that if we get
+        * PHY_INTERFACE_MODE_NA, we must return all modes we support.  Because
+        * of this, NA starts at the top of the switch and falls all the way to
+        * the bottom, and doesn't return early if we don't support a
+        * particular mode.
+        */
+       switch (state->interface) {
+       case PHY_INTERFACE_MODE_NA:
+       case PHY_INTERFACE_MODE_10GBASER:
+               if (bp->caps & MACB_CAPS_HIGH_SPEED &&
+                   bp->caps & MACB_CAPS_PCS &&
+                   bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE) {
+                       phylink_set_10g_modes(mask);
+                       phylink_set(mask, 10000baseKR_Full);
+               } else if (one) {
+                       bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
+                       return;
+               }
+               if (one)
+                       break;

This can go in the first if block.

+               fallthrough;
+       case PHY_INTERFACE_MODE_GMII:
+       case PHY_INTERFACE_MODE_RGMII:
+       case PHY_INTERFACE_MODE_RGMII_ID:
+       case PHY_INTERFACE_MODE_RGMII_RXID:
+       case PHY_INTERFACE_MODE_RGMII_TXID:
+       case PHY_INTERFACE_MODE_SGMII:
+               if (macb_is_gem(bp)) {
+                       if (bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE) {

Is not having MACB_CAPS_GIGABIT_MODE_AVAILABLE acceptable here, or
should the two above checks be merged?

+                               phylink_set(mask, 1000baseT_Full);
+                               phylink_set(mask, 1000baseX_Full);
+                               if (!(bp->caps & MACB_CAPS_NO_GIGABIT_HALF))
+                                       phylink_set(mask, 1000baseT_Half);
+                       }
+               } else if (one) {
+                       bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
+                       return;
+               }
+               fallthrough;
+       case PHY_INTERFACE_MODE_MII:
+       case PHY_INTERFACE_MODE_RMII:
+               phylink_set(mask, 10baseT_Half);
+               phylink_set(mask, 10baseT_Full);
+               phylink_set(mask, 100baseT_Half);
+               phylink_set(mask, 100baseT_Full);
+               break;
+       default:
                bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
                return;
        }

(For readability, it's not for me to decide in the end).

Thanks,
Antoine

On 10/13/21 4:29 AM, Antoine Tenart wrote:

Quoting Sean Anderson (2021-10-12 21:46:44)

quoted

+       /* There are three major types of interfaces we support:
+        * - (R)MII supporting 10/100 Mbit/s
+        * - GMII, RGMII, and SGMII supporting 10/100/1000 Mbit/s
+        * - 10GBASER supporting 10 Gbit/s only
+        * Because GMII and MII both support 10/100, GMII falls through to MII.
+        *
+        * If we can't support an interface mode, we just clear the supported
+        * mask and return. The major complication is that if we get
+        * PHY_INTERFACE_MODE_NA, we must return all modes we support.  Because
+        * of this, NA starts at the top of the switch and falls all the way to
+        * the bottom, and doesn't return early if we don't support a
+        * particular mode.
+        */
+       switch (state->interface) {
+       case PHY_INTERFACE_MODE_NA:
+       case PHY_INTERFACE_MODE_10GBASER:
+               if (bp->caps & MACB_CAPS_HIGH_SPEED &&
+                   bp->caps & MACB_CAPS_PCS &&
+                   bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE) {
+                       phylink_set_10g_modes(mask);
+                       phylink_set(mask, 10000baseKR_Full);
+               } else if (one) {
+                       bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
+                       return;
+               }
+               if (one)
+                       break;

This can go in the first if block.

OK.

quoted

+               fallthrough;
+       case PHY_INTERFACE_MODE_GMII:
+       case PHY_INTERFACE_MODE_RGMII:
+       case PHY_INTERFACE_MODE_RGMII_ID:
+       case PHY_INTERFACE_MODE_RGMII_RXID:
+       case PHY_INTERFACE_MODE_RGMII_TXID:
+       case PHY_INTERFACE_MODE_SGMII:
+               if (macb_is_gem(bp)) {
+                       if (bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE) {

Is not having MACB_CAPS_GIGABIT_MODE_AVAILABLE acceptable here, or
should the two above checks be merged?

As I understand it, macb_is_gem does not imply GIGABIT_MODE. I'm not
sure if GIGABIT_MODE implies macb_is_gem. The logic here is mostly to
match that in prepare()/config(). From what I can gather, all accesses
to GEM registers are protected by macb_is_gem.

--Sean

quoted

+                               phylink_set(mask, 1000baseT_Full);
+                               phylink_set(mask, 1000baseX_Full);
+                               if (!(bp->caps & MACB_CAPS_NO_GIGABIT_HALF))
+                                       phylink_set(mask, 1000baseT_Half);
+                       }
+               } else if (one) {
+                       bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
+                       return;
+               }
+               fallthrough;
+       case PHY_INTERFACE_MODE_MII:
+       case PHY_INTERFACE_MODE_RMII:
+               phylink_set(mask, 10baseT_Half);
+               phylink_set(mask, 10baseT_Full);
+               phylink_set(mask, 100baseT_Half);
+               phylink_set(mask, 100baseT_Full);
+               break;
+       default:
                bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
                return;
        }

(For readability, it's not for me to decide in the end).

Thanks,
Antoine