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f3b766d981
The CBTX PHY is a Fast Ethernet PHY integrated into the SJA1110 A/B/C automotive Ethernet switches. It was hoped it would work with the Generic PHY driver, but alas, it doesn't. The most important reason why is that the PHY is powered down by default, and it needs a vendor register to power it on. It has a linear memory map that is accessed over SPI by the SJA1110 switch driver, which exposes a fake MDIO controller. It has the following (and only the following) standard clause 22 registers: 0x0: MII_BMCR 0x1: MII_BMSR 0x2: MII_PHYSID1 0x3: MII_PHYSID2 0x4: MII_ADVERTISE 0x5: MII_LPA 0x6: MII_EXPANSION 0x7: the missing MII_NPAGE for Next Page Transmit Register Every other register is vendor-defined. The register map expands the standard clause 22 5-bit address space of 0x20 registers, however the driver does not need to access the extra registers for now (and hopefully never). If it ever needs to do that, it is possible to implement a fake (software) page switching mechanism between the PHY driver and the SJA1110 MDIO controller driver. Also, Auto-MDIX is turned off by default in hardware, the driver turns it on by default and reports the current status. I've tested this with a VSC8514 link partner and a crossover cable, by forcing the mode on the link partner, and seeing that the CBTX PHY always sees the reverse of the mode forced on the VSC8514 (and that traffic works). The link doesn't come up (as expected) if MDI modes are forced on both ends in the same way (with the cross-over cable, that is). Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Link: https://lore.kernel.org/r/20230418190141.1040562-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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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.