Coia Prant 2efa9f57d0 net: pcs: xpcs: fix SGMII state reading
commit def9a4745e upstream.

Commit 2a22b7ae2f ("net: pcs: xpcs: adapt Wangxun NICs for SGMII mode")
added a path in xpcs_get_state_c37_sgmii() that reads speed/duplex from
BMCR after AN completes. However, BMCR does not reflect the negotiated
result on the hardware where this has been tested:

- On RK3568 (MAC side SGMII), BMCR returns a fixed hardware reset value
- Wangxun engineer Jiawen Wu confirmed that on their side, "BMCR looks
  like it only wants to be return as 0" [0]

The correct information is available in CL37_ANSGM_STS, which contains
the actual link status and negotiated speed/duplex.

This bug was previously masked by phylink core, which overrides the PCS
link state with the PHY state when a PHY is present:

        /* If we have a phy, the "up" state is the union of both the
         * PHY and the MAC
         */
        if (phy)
                link_state.link &= pl->phy_state.link;

Thus, when the link is down, the PHY's link_down state is applied on top
of whatever the PCS reports, hiding the broken PCS state reading path.

Modify xpcs_get_state_c37_sgmii() to:
1. Read link state from CL37_ANSGM_STS
2. If link is up, report speed/duplex from CL37_ANSGM_STS
3. Remove the broken BMCR reading path entirely

Also properly set state->an_complete to reflect the AN completion status,
and clear CL37_ANCMPLT_INTR when link is down to avoid stale state.

[0] https://lore.kernel.org/all/000c01dd1593$2ac0b0f0$804212d0$@trustnetic.com/

Fixes: 2a22b7ae2f ("net: pcs: xpcs: adapt Wangxun NICs for SGMII mode")
Cc: stable@vger.kernel.org
Tested-by: Jiawen Wu <jiawenwu@trustnetic.com>
Signed-off-by: Coia Prant <coiaprant@gmail.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20260717074324.3250043-2-coiaprant@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2026-08-03 11:15:33 +02:00
2026-07-24 16:03:06 +02:00
2026-05-23 13:03:09 +02:00
…
…
…
…
…
…
2026-05-23 13:03:09 +02:00
2026-07-30 13:02:12 +02:00
…

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.
S
Description
No description provided
Readme
5.7 GiB
Languages
C 96.9%
Assembly 0.9%
Rust 0.6%
Shell 0.6%
Python 0.5%
Other 0.3%