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Vladimir Oltean 36d9b54258 net: cpsw: convert to ndo_hwtstamp_get() and ndo_hwtstamp_set() 
New timestamping API was introduced in commit 66f7223039 ("net: add
NDOs for configuring hardware timestamping") from kernel v6.6. It is
time to convert the two cpsw drivers to the new API, so that the
ndo_eth_ioctl() path can be removed completely.

The cpsw_hwtstamp_get() and cpsw_hwtstamp_set() methods (and their shim
definitions, for the case where CONFIG_TI_CPTS is not enabled) must have
their prototypes adjusted.

These methods are used by two drivers (cpsw and cpsw_new), with vastly
different configurations:
- cpsw has two operating modes:
  - "dual EMAC" - enabled through the "dual_emac" device tree property -
    creates one net_device per EMAC / slave interface (but there is no
    bridging offload)
  - "switch mode" - default - there is a single net_device, with two
    EMACs/slaves behind it (and switching between them happens
    unbeknownst to the network stack).
- cpsw_new always registers one net_device for each EMAC which doesn't
  have status = "disabled". In terms of switching, it has two modes:
  - "dual EMAC": default, no switching between ports, no switchdev
    offload.
  - "switch mode": enabled through the "switch_mode" devlink parameter,
    offloads the Linux bridge through switchdev

Essentially, in 3 out of 4 operating modes, there is a bijective
relation between the net_device and the slave. Timestamping can thus be
configured on individual slaves. But in the "switch mode" of the cpsw
driver, ndo_eth_ioctl() targets a single slave, designated using the
"active_slave" device tree property.

To deal with these different cases, the common portion of the drivers,
cpsw_priv.c, has the cpsw_slave_index() function pointer, set to
separate, identically named cpsw_slave_index_priv() by the 2 drivers.

This is all relevant because cpsw_ndo_ioctl() has the old-style
phy_has_hwtstamp() logic which lets the PHY handle the timestamping
ioctls. Normally, that logic should be obsoleted by the more complex
logic in the core, which permits dynamically selecting the timestamp
provider - see dev_set_hwtstamp_phylib().

But I have doubts as to how this works for the "switch mode" of the dual
EMAC driver, because the core logic only engages if the PHY is visible
through ndev->phydev (this is set by phy_attach_direct()).

In cpsw.c, we have:
cpsw_ndo_open()
-> for_each_slave(priv, cpsw_slave_open, priv); // continues on errors
   -> of_phy_connect()
      -> phy_connect_direct()
         -> phy_attach_direct()
   OR
   -> phy_connect()
      -> phy_connect_direct()
         -> phy_attach_direct()

The problem for "switch mode" is that the behavior of phy_attach_direct()
called twice in a row for the same net_device (once for each slave) is
probably undefined.

For sure it will overwrite dev->phydev. I don't see any explicit error
checks for this case, and even if there were, the for_each_slave() call
makes them non-fatal to cpsw_ndo_open() anyway.

I have no idea what is the extent to which this provides a usable
result, but the point is: only the last attached PHY will be visible
in dev->phydev, and this may well be a different PHY than
cpsw->slaves[slave_no].phy for the "active_slave".

In dual EMAC mode, as well as in cpsw_new, this should not be a problem.
I don't know whether PHY timestamping is a use case for the cpsw "switch
mode" as well, and I hope that there isn't, because for the sake of
simplicity, I've decided to deliberately break that functionality, by
refusing all PHY timestamping. Keeping it would mean blocking the old
API from ever being removed. In the new dev_set_hwtstamp_phylib() API,
it is not possible to operate on a phylib PHY other than dev->phydev,
and I would very much prefer not adding that much complexity for bizarre
driver decisions.

Final point about the cpsw_hwtstamp_get() conversion: we don't need to
propagate the unnecessary "config.flags = 0;", because dev_get_hwtstamp()
provides a zero-initialized struct kernel_hwtstamp_config.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20250512114422.4176010-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-05-14 19:41:46 -07:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-08 08:59:02 -07:00
block block-6.15-20250424 2025-04-25 11:34:39 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-01 15:11:38 -07:00
Documentation dt-bindings: net: snps,dwmac: Align mdio node in example with bindings 2025-05-14 18:51:58 -07:00
drivers net: cpsw: convert to ndo_hwtstamp_get() and ndo_hwtstamp_set() 2025-05-14 19:41:46 -07:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-08 08:59:02 -07:00
include net: phy: remove stub for mdiobus_register_board_info 2025-05-13 16:39:45 -07:00
init Kconfig: switch CONFIG_SYSFS_SYCALL default to n 2025-04-15 10:28:35 +02:00
io_uring net: devmem: Implement TX path 2025-05-13 11:12:48 +02:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-08 08:59:02 -07:00
lib hardening fixes for v6.15-rc3 2025-04-18 13:20:20 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-08 08:59:02 -07:00
net openvswitch: Stricter validation for the userspace action 2025-05-14 19:13:34 -07:00
rust Driver core fixes for 6.15-rc4 2025-04-25 10:02:59 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-01 15:11:38 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-01 15:11:38 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-01 15:11:38 -07:00
sound ASoC: Fixes for v6.15 2025-05-01 10:22:20 +02:00
tools tools: ynl-gen: support struct for binary attributes 2025-05-13 13:22:32 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-05 04:06:45 +09:00
virt ARM: 2025-04-08 13:47:55 -07:00
.clang-format clang-format: Update the ForEachMacros list for v6.15-rc1 2025-04-13 11:03:59 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-01-10 00:17:25 +01:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes
.gitignore kbuild: Create intermediate vmlinux build with relocations preserved 2025-03-17 00:29:50 +09:00
.mailmap sound fixes for 6.15-rc3 2025-04-17 10:14:51 -07:00
.rustfmt.toml
COPYING
CREDITS MAINTAINERS: update SLAB ALLOCATOR maintainers 2025-04-17 20:10:06 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/linux 2025-05-12 18:48:27 -07:00
Makefile Linux 6.15-rc5 2025-05-04 13:55:04 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

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 reStructuredText 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.