[PATCH 6.6 012/143] net: dpaa: fman_memac: accept phy-interface-type = "10gbase-r" in the device tree

Greg Kroah-Hartman
2024-03-04T21:36:28Z

From: Vladimir Oltean <vladimir.oltean@nxp.com>

[ Upstream commit 734f06db599f66d6a159c78abfdbadfea3b7d43b ]

Since commit 5d93cfcf7360 ("net: dpaa: Convert to phylink"), we support
the "10gbase-r" phy-mode through a driver-based conversion of "xgmii",
but we still don't actually support it when the device tree specifies
"10gbase-r" proper.

This is because boards such as LS1046A-RDB do not define pcs-handle-names
(for whatever reason) in the ethernet@f0000 device tree node, and the
code enters through this code path:

err = of_property_match_string(mac_node, "pcs-handle-names", "xfi");
// code takes neither branch and falls through
if (err >= 0) {
(...)
} else if (err != -EINVAL && err != -ENODATA) {
goto _return_fm_mac_free;
}

(...)

/* For compatibility, if pcs-handle-names is missing, we assume this
* phy is the first one in pcsphy-handle
*/
err = of_property_match_string(mac_node, "pcs-handle-names", "sgmii");
if (err == -EINVAL || err == -ENODATA)
pcs = memac_pcs_create(mac_node, 0); // code takes this branch
else if (err < 0)
goto _return_fm_mac_free;
else
pcs = memac_pcs_create(mac_node, err);

// A default PCS is created and saved in "pcs"

// This determination fails and mistakenly saves the default PCS
// memac->sgmii_pcs instead of memac->xfi_pcs, because at this
// stage, mac_dev->phy_if == PHY_INTERFACE_MODE_10GBASER.
if (err && mac_dev->phy_if == PHY_INTERFACE_MODE_XGMII)
memac->xfi_pcs = pcs;
else
memac->sgmii_pcs = pcs;

In other words, in the absence of pcs-handle-names, the default
xfi_pcs assignment logic only works when in the device tree we have
PHY_INTERFACE_MODE_XGMII.

By reversing the order between the fallback xfi_pcs assignment and the
"xgmii" overwrite with "10gbase-r", we are able to support both values
in the device tree, with identical behavior.

Currently, it is impossible to make the s/xgmii/10gbase-r/ device tree
conversion, because it would break forward compatibility (new device
tree with old kernel). The only way to modify existing device trees to
phy-interface-mode = "10gbase-r" is to fix stable kernels to accept this
value and handle it properly.

One reason why the conversion is desirable is because with pre-phylink
kernels, the Aquantia PHY driver used to warn about the improper use
of PHY_INTERFACE_MODE_XGMII [1]. It is best to have a single (latest)
device tree that works with all supported stable kernel versions.

Note that the blamed commit does not constitute a regression per se.
Older stable kernels like 6.1 still do not work with "10gbase-r", but
for a different reason. That is a battle for another time.

[1] https://lore.kernel.org/netdev/20240214-ls1046-dts-use-10gbase-r-v1-1-8c2d68547393@concurrent-rt.com/

Fixes: 5d93cfcf7360 ("net: dpaa: Convert to phylink")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Madalin Bucur <madalin.bucur@oss.nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../net/ethernet/freescale/fman/fman_memac.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fman/fman_memac.c b/drivers/net/ethernet/freescale/fman/fman_memac.c
index 3b75cc543be93..76e5181789cb9 100644
--- a/drivers/net/ethernet/freescale/fman/fman_memac.c
+++ b/drivers/net/ethernet/freescale/fman/fman_memac.c
@@ -1074,6 +1074,14 @@ int memac_initialization(struct mac_device *mac_dev,
unsigned long capabilities;
unsigned long *supported;

+ /* The internal connection to the serdes is XGMII, but this isn't
+ * really correct for the phy mode (which is the external connection).
+ * However, this is how all older device trees say that they want
+ * 10GBASE-R (aka XFI), so just convert it for them.
+ */
+ if (mac_dev->phy_if == PHY_INTERFACE_MODE_XGMII)
+ mac_dev->phy_if = PHY_INTERFACE_MODE_10GBASER;
+
mac_dev->phylink_ops = &memac_mac_ops;
mac_dev->set_promisc = memac_set_promiscuous;
mac_dev->change_addr = memac_modify_mac_address;
@@ -1140,7 +1148,7 @@ int memac_initialization(struct mac_device *mac_dev,
* (and therefore that xfi_pcs cannot be set). If we are defaulting to
* XGMII, assume this is for XFI. Otherwise, assume it is for SGMII.
*/
- if (err && mac_dev->phy_if == PHY_INTERFACE_MODE_XGMII)
+ if (err && mac_dev->phy_if == PHY_INTERFACE_MODE_10GBASER)
memac->xfi_pcs = pcs;
else
memac->sgmii_pcs = pcs;
@@ -1154,14 +1162,6 @@ int memac_initialization(struct mac_device *mac_dev,
goto _return_fm_mac_free;
}

- /* The internal connection to the serdes is XGMII, but this isn't
- * really correct for the phy mode (which is the external connection).
- * However, this is how all older device trees say that they want
- * 10GBASE-R (aka XFI), so just convert it for them.
- */
- if (mac_dev->phy_if == PHY_INTERFACE_MODE_XGMII)
- mac_dev->phy_if = PHY_INTERFACE_MODE_10GBASER;
-
/* TODO: The following interface modes are supported by (some) hardware
* but not by this driver:
* - 1000BASE-KX
--
2.43.0