Vladimir Oltean
5c71729ab9
On a port with SGMII fixed-link at SPEED_1000, DW_VR_MII_DIG_CTRL1 gets
set to 0x2404. This is incorrect, because bit 2 (DW_VR_MII_DIG_CTRL1_2G5_EN)
is set.
It comes from the previous write to DW_VR_MII_AN_CTRL, because the "val"
variable is reused and is dirty. Actually, its value is 0x4, aka
FIELD_PREP(DW_VR_MII_PCS_MODE_MASK, DW_VR_MII_PCS_MODE_C37_SGMII).
Resolve the issue by clearing "val" to 0 when writing to a new register.
After the fix, the register value is 0x2400.
Prior to the blamed commit, when the read-modify-write was open-coded,
the code saved the content of the DW_VR_MII_DIG_CTRL1 register in the
"ret" variable.
Fixes: ce8d6081fc ("net: pcs: xpcs: add _modify() accessors")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/20250114164721.2879380-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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.