mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/
synced 2026-10-28 20:03:05 +00:00
No description
- C 96.8%
- Assembly 0.9%
- Rust 0.7%
- Shell 0.6%
- Python 0.5%
- Other 0.3%
0c2a4d304c
Russell King says: ==================== net: stmmac: remove mac_interface The dwmac core supports a range of interfaces, but when it comes to SerDes interfaces, the core itself does not include the SerDes block. Consequently, it has to provide an interface suitable to interface such a block to, and uses TBI for this. The driver also uses "PCS" for RGMII, even though the dwmac PCS block is not present for this interface type - it was a convenice for the code structure as RGMII includes inband signalling of the PHY state, much like Cisco SGMII does at a high level. As such, the code refers to RGMII and SGMII modes for the PCS, and there used to be STMMAC_PCS_TBI and STMMAC_PCS_RTBI constants as well but these were never set, although they were used in the code. The selection of the PCS mode was from mac_interface. Thus, it seems that the original intention was for mac_interface to describe the interface mode used within the dwmac core, and phy_interface to describe the external world-accessible interface (e.g. which would connect to a PHY or SFP cage.) It appears that many glue drivers misinterpret these. A good exmple is socfpga. This supports SGMII and 1000BASE-X, but does not include the dwmac PCS, relying on the Lynx PCS instead. However, it makes use of mac_interface to configure the dwmac core to its GMII/MII mode. So, when operating in either of these modes, the dwmac is configured for GMII mode to communicate with the Lynx PCS which then provides the SGMII or 1000BASE-X interface mode to the external world. Given that phy_interface is the external world interface, and mac_interface is the dwmac core interface, selecting the interface mode based on mac_interface being 1000BASEX makes no sense. Moreover, mac_interface is initialised by the stmmac core code. If the "mac-mode" property is set in DT, this will be used. Otherwise, it will reflect the "phy-mode" property - meaning that it defaults to phy_interface. As no in-kernel DT makes reference to a "mac-mode" property, we can assume that for all in-kernel platforms, these two interface variables are the same. The exception are those platform glues which I reviwed and suggested they use phy_interface, setting mac_interface to PHY_INTERFACE_MODE_NA. The conclusion to all of this is that mac_interface serves no useful purpose, and causes confusion as the platform glue code doesn't seem to know which one should be used. Thus, let's get rid of mac_interface, which makes all this code more understandable. It also helps to untangle some of the questions such as: - should this be using the interface passed from phylink - should we set the range of phylink supported interfaces to be more than one - when we get phylink PCS support for the dwmac PCS, should we be selecting it based on mac_interface or phy_interface, and how should we populate the PCS' supported_interface bitmap. Having converted socfpga to use phy_interface, this turns out to feel like "the right way" to do this - convert the external world "phy_interface" to whatever phy_intf_sel value that the dwmac core needs to achieve the connection to whatever hardware blocks are integrated inside the SoC to achieve the requested external world interface. As an illustration why - consider that in the case of socfpga, it _could_ have been implemented such that the dwmac PCS was used for SGMII, and the Lynx PCS for 1000BASE-X, or vice versa. Only the platform glue would know which it is. I will also note that several cores provide their currently configured interface mode via the ACTPHYIF field of Hardware Feature 0, and thus can be read back in the platform-independent parts of the driver to decide whether the internal PCS or the RGMII (or actually SMII) "PCS" should be used. This is hot-off-the-press, and has only been build tested. As I have none of these platforms, this series has not been run-tested, so please test on your hardware. ==================== Link: https://patch.msgid.link/aMrPpc8oRxqGtVPJ@shell.armlinux.org.uk Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
History
|
|
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.