From 4352b8aee98005853aa63f57d6377282de17a33f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 23 Aug 2026 13:28:57 -0700 Subject: Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ... --- Documentation/networking/netif-msg.rst | 95 ++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) create mode 100644 Documentation/networking/netif-msg.rst (limited to 'Documentation/networking/netif-msg.rst') diff --git a/Documentation/networking/netif-msg.rst b/Documentation/networking/netif-msg.rst new file mode 100644 index 000000000..b20d265a7 --- /dev/null +++ b/Documentation/networking/netif-msg.rst @@ -0,0 +1,95 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============== +NETIF Msg Level +=============== + +The design of the network interface message level setting. + +History +------- + + The design of the debugging message interface was guided and + constrained by backwards compatibility previous practice. It is useful + to understand the history and evolution in order to understand current + practice and relate it to older driver source code. + + From the beginning of Linux, each network device driver has had a local + integer variable that controls the debug message level. The message + level ranged from 0 to 7, and monotonically increased in verbosity. + + The message level was not precisely defined past level 3, but were + always implemented within +-1 of the specified level. Drivers tended + to shed the more verbose level messages as they matured. + + - 0 Minimal messages, only essential information on fatal errors. + - 1 Standard messages, initialization status. No run-time messages + - 2 Special media selection messages, generally timer-driver. + - 3 Interface starts and stops, including normal status messages + - 4 Tx and Rx frame error messages, and abnormal driver operation + - 5 Tx packet queue information, interrupt events. + - 6 Status on each completed Tx packet and received Rx packets + - 7 Initial contents of Tx and Rx packets + + Initially this message level variable was uniquely named in each driver + e.g. "lance_debug", so that a kernel symbolic debugger could locate and + modify the setting. When kernel modules became common, the variables + were consistently renamed to "debug" and allowed to be set as a module + parameter. + + This approach worked well. However there is always a demand for + additional features. Over the years the following emerged as + reasonable and easily implemented enhancements + + - Using an ioctl() call to modify the level. + - Per-interface rather than per-driver message level setting. + - More selective control over the type of messages emitted. + + The netif_msg recommendation adds these features with only a minor + complexity and code size increase. + + The recommendation is the following points + + - Retaining the per-driver integer variable "debug" as a module + parameter with a default level of '1'. + + - Adding a per-interface private variable named "msg_enable". The + variable is a bit map rather than a level, and is initialized as:: + + 1 << debug + + Or more precisely:: + + debug < 0 ? 0 : 1 << min(sizeof(int)-1, debug) + + Messages should changes from:: + + if (debug > 1) + printk(MSG_DEBUG "%s: ... + + to:: + + if (np->msg_enable & NETIF_MSG_LINK) + printk(MSG_DEBUG "%s: ... + + +The set of message levels is named + + + ========= =================== ============ + Old level Name Bit position + ========= =================== ============ + 0 NETIF_MSG_DRV 0x0001 + 1 NETIF_MSG_PROBE 0x0002 + 2 NETIF_MSG_LINK 0x0004 + 2 NETIF_MSG_TIMER 0x0004 + 3 NETIF_MSG_IFDOWN 0x0008 + 3 NETIF_MSG_IFUP 0x0008 + 4 NETIF_MSG_RX_ERR 0x0010 + 4 NETIF_MSG_TX_ERR 0x0010 + 5 NETIF_MSG_TX_QUEUED 0x0020 + 5 NETIF_MSG_INTR 0x0020 + 6 NETIF_MSG_TX_DONE 0x0040 + 6 NETIF_MSG_RX_STATUS 0x0040 + 7 NETIF_MSG_PKTDATA 0x0080 + ========= =================== ============ -- cgit v1.3.1