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authorNiklas Cassel <cassel@kernel.org>2026-09-16 15:00:32 +0200
committerNiklas Cassel <cassel@kernel.org>2026-09-16 16:18:00 +0200
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ata: libata-scsi: fix ata_dsm_trim_pages() kernel-docgrafted
make htmldocs fails with: Documentation/driver-api/libata:604: ./drivers/ata/libata-scsi.c:2301: ERROR: Unexpected indentation. [docutils] The Return: section of ata_dsm_trim_pages() ends its first sentence with a colon and continues with an indented bullet list. reStructuredText requires a blank line before an indented block, so docutils chokes on the list. Simply adding the missing blank line does not work either: Return: is a kernel-doc "special section", which is terminated by the first blank line, so the bullet list would end up in the Description section, detached from the sentence introducing it. Spell the two bounds out as prose instead, so that the Return: section stays self-contained. Documentation-only change. Fixes: e64e6b5dc867 ("ata: libata-scsi: scale DSM TRIM payload by MAX PAGES PER DSM COMMAND") Reported-by: Thomas Huth <thuth@redhat.com> Closes: https://lore.kernel.org/linux-ide/b0a0b8e8-cc4f-4c7b-8bc5-fee0712d405a@redhat.com/ Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Thomas Huth <thuth@redhat.com> Link: https://lore.kernel.org/r/20260916130031.29990-2-cassel@kernel.org Signed-off-by: Niklas Cassel <cassel@kernel.org>
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+.. SPDX-License-Identifier: GPL-2.0
+
+===================================
+GPIO Character Device Userspace API
+===================================
+
+This is latest version (v2) of the character device API, as defined in
+``include/uapi/linux/gpio.h.``
+
+First added in 5.10.
+
+.. note::
+ Do NOT abuse userspace APIs to control hardware that has proper kernel
+ drivers. There may already be a driver for your use case, and an existing
+ kernel driver is sure to provide a superior solution to bitbashing
+ from userspace.
+
+ Read Documentation/driver-api/gpio/drivers-on-gpio.rst to avoid reinventing
+ kernel wheels in userspace.
+
+ Similarly, for multi-function lines there may be other subsystems, such as
+ Documentation/spi/index.rst, Documentation/i2c/index.rst,
+ Documentation/driver-api/pwm.rst, Documentation/w1/index.rst etc, that
+ provide suitable drivers and APIs for your hardware.
+
+Basic examples using the character device API can be found in ``tools/gpio/*``.
+
+The API is based around two major objects, the :ref:`gpio-v2-chip` and the
+:ref:`gpio-v2-line-request`.
+
+.. _gpio-v2-chip:
+
+Chip
+====
+
+The Chip represents a single GPIO chip and is exposed to userspace using device
+files of the form ``/dev/gpiochipX``.
+
+Each chip supports a number of GPIO lines,
+:c:type:`chip.lines<gpiochip_info>`. Lines on the chip are identified by an
+``offset`` in the range from 0 to ``chip.lines - 1``, i.e. `[0,chip.lines)`.
+
+Lines are requested from the chip using gpio-v2-get-line-ioctl.rst
+and the resulting line request is used to access the GPIO chip's lines or
+monitor the lines for edge events.
+
+Within this documentation, the file descriptor returned by calling `open()`
+on the GPIO device file is referred to as ``chip_fd``.
+
+Operations
+----------
+
+The following operations may be performed on the chip:
+
+.. toctree::
+ :titlesonly:
+
+ Get Line <gpio-v2-get-line-ioctl>
+ Get Chip Info <gpio-get-chipinfo-ioctl>
+ Get Line Info <gpio-v2-get-lineinfo-ioctl>
+ Watch Line Info <gpio-v2-get-lineinfo-watch-ioctl>
+ Unwatch Line Info <gpio-get-lineinfo-unwatch-ioctl>
+ Read Line Info Changed Events <gpio-v2-lineinfo-changed-read>
+
+.. _gpio-v2-line-request:
+
+Line Request
+============
+
+Line requests are created by gpio-v2-get-line-ioctl.rst and provide
+access to a set of requested lines. The line request is exposed to userspace
+via the anonymous file descriptor returned in
+:c:type:`request.fd<gpio_v2_line_request>` by gpio-v2-get-line-ioctl.rst.
+
+Within this documentation, the line request file descriptor is referred to
+as ``req_fd``.
+
+Operations
+----------
+
+The following operations may be performed on the line request:
+
+.. toctree::
+ :titlesonly:
+
+ Get Line Values <gpio-v2-line-get-values-ioctl>
+ Set Line Values <gpio-v2-line-set-values-ioctl>
+ Read Line Edge Events <gpio-v2-line-event-read>
+ Reconfigure Lines <gpio-v2-line-set-config-ioctl>
+
+Types
+=====
+
+This section contains the structs and enums that are referenced by the API v2,
+as defined in ``include/uapi/linux/gpio.h``.
+
+.. kernel-doc:: include/uapi/linux/gpio.h
+ :identifiers:
+ gpio_v2_line_attr_id
+ gpio_v2_line_attribute
+ gpio_v2_line_changed_type
+ gpio_v2_line_config
+ gpio_v2_line_config_attribute
+ gpio_v2_line_event
+ gpio_v2_line_event_id
+ gpio_v2_line_flag
+ gpio_v2_line_info
+ gpio_v2_line_info_changed
+ gpio_v2_line_request
+ gpio_v2_line_values
+ gpiochip_info
+
+.. toctree::
+ :hidden:
+
+ error-codes