734f06db59
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.