mainlining shenanigans
388ca27ffd
Sven Auhagen reported issues with negotiation on a couple of his platforms using a mixture of SFP and PHYs in various different modes. Debugging to root cause proved difficult, but essentially the problem comes down to the mvpp2 phylink implementation being slightly at odds with what is expected. phylink operates in three modes: phy, fixed-link, and in-band mode. In the first two modes, the expected behaviour from a MAC driver is that phylink resolves the operating mode and passes the mode to the MAC driver for it to program, including when the link should be brought up or taken down. This is basically the same as the libphy approach. This does not negate the requirement to advertise a correct control word for interface modes that have control words where that can be reasonably controlled. The second mode is in-band mode, where the MAC is expected to use the in-band control word to determine the operating mode. The mvneta driver implements the correct pattern required to support this: configure the port interface type separately from the in-band mode(s). This is now specified in the phylink documentation patches. mvpp2 was programming in-band mode for SGMII and the 802.3z modes no what, and avoided forcing the link up in fixed/phy modes. This caused a problem with some boards where the PHY is by default programmed to enter AN bypass mode, the PHY would report that the link was up, but the mvpp2 never completed the exchange of control word. Another issue that mvpp2 has is it sets SGMII AN format control word for both SGMII and 802.3z modes. The format of the control word is defined by MVPP2_GMAC_INBAND_AN_MASK, which should be set for SGMII and clear for 802.3z. Available Marvell documentation for earlier GMAC implementations does not make this clear, but this has been ascertained via extensive testing on earlier GMAC implementations, and then confirmed with a Macchiatobin Single Shot connected to a Clearfog: when MVPP2_GMAC_INBAND_AN_MASK is set, the clearfog does not receive the advertised pause mode settings. Lastly, there is no flow control in the in-band control word in Cisco SGMII, setting the flow control autonegotiation bit even with a PHY that has the Marvell extension to send this information does not result in the flow control being enabled at the MAC. We need to do this manually using the information provided via phylink. Re-code mvpp2's mac_config() and mac_link_up() to follow this pattern. This allows Sven Auhagen's board and Macchiatobin to reliably bring the link up with the 88e1512 PHY with phylink operating in PHY mode with COMPHY built as a module but the rest of the networking built-in, and u-boot having brought up the interface. in-band mode requires an additional patch to resolve another problem. Tested-by: Sven Auhagen <sven.auhagen@voleatech.de> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
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| lib | ||
| LICENSES | ||
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| net | ||
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| .clang-format | ||
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| 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 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.