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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
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tree27614d7a9ef05c32d089004e104364ce42324837 /Documentation/ABI/testing/sysfs-auxdisplay-linedisp
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Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
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 ...
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+What: /sys/.../message
+Date: October 2021
+KernelVersion: 5.16
+Description:
+ Controls the text message displayed on character line displays.
+
+ Reading returns the current message with a trailing newline.
+ Writing updates the displayed message. Messages longer than the
+ display width will automatically scroll. Trailing newlines in
+ input are automatically trimmed.
+
+ Writing an empty string clears the display.
+
+ Example:
+ echo "Hello World" > message
+ cat message # Returns "Hello World\n"
+
+What: /sys/.../num_chars
+Date: November 2025
+KernelVersion: 6.18
+Contact: Jean-François Lessard <jefflessard3@gmail.com>
+Description:
+ Read-only attribute showing the character width capacity of
+ the line display device. Messages longer than this will scroll.
+
+ Example:
+ cat num_chars # Returns "16\n" for 16-char display
+
+What: /sys/.../scroll_step_ms
+Date: October 2021
+KernelVersion: 5.16
+Description:
+ Controls the scrolling speed for messages longer than the display
+ width, specified in milliseconds per scroll step.
+
+ Setting to 0 disables scrolling. Default is 500ms.
+
+ Example:
+ echo "250" > scroll_step_ms # 4Hz scrolling
+ cat scroll_step_ms # Returns "250\n"
+
+What: /sys/.../map_seg7
+Date: January 2024
+KernelVersion: 6.9
+Description:
+ Read/write binary blob representing the ASCII-to-7-segment
+ display conversion table used by the linedisp driver, as defined
+ by struct seg7_conversion_map in <linux/map_to_7segment.h>.
+
+ Only visible on displays with 7-segment capability.
+
+ This attribute is not human-readable. Writes must match the
+ struct size exactly, else -EINVAL is returned; reads return the
+ entire mapping as a binary blob.
+
+ This interface and its implementation match existing conventions
+ used in segment-mapped display drivers since 2005.
+
+ ABI note: This style of binary sysfs attribute *is an exception*
+ to current "one value per file, text only" sysfs rules, for
+ historical compatibility and driver uniformity. New drivers are
+ discouraged from introducing additional binary sysfs ABIs.
+
+ Reference interface guidance:
+ - include/uapi/linux/map_to_7segment.h
+
+What: /sys/.../map_seg14
+Date: January 2024
+KernelVersion: 6.9
+Description:
+ Read/write binary blob representing the ASCII-to-14-segment
+ display conversion table used by the linedisp driver, as defined
+ by struct seg14_conversion_map in <linux/map_to_14segment.h>.
+
+ Only visible on displays with 14-segment capability.
+
+ This attribute is not human-readable. Writes must match the
+ struct size exactly, else -EINVAL is returned; reads return the
+ entire mapping as a binary blob.
+
+ This interface and its implementation match existing conventions
+ used by segment-mapped display drivers since 2005.
+
+ ABI note: This style of binary sysfs attribute *is an exception*
+ to current "one value per file, text only" sysfs rules, for
+ historical compatibility and driver uniformity. New drivers are
+ discouraged from introducing additional binary sysfs ABIs.
+
+ Reference interface guidance:
+ - include/uapi/linux/map_to_14segment.h