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path: root/Documentation/userspace-api/gpio/sysfs.rst
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2024-06-10docs: gpio: prefer pread(2) for interrupt readingHuichun Feng
In legacy sysfs GPIO, when using poll(2) on the sysfs GPIO value for state change awaiting, a subsequent read(2) is required for consuming the event, which the doc recommends the use of lseek(2) or close-and-reopen to reset the file offset afterwards. The recommendations however, require at least 2 syscalls to consume the event. Gladly, use of pread(2) require only 1 syscall for the consumption. Let's advertise this usage by prioritizing its placement. Signed-off-by: Huichun Feng <foxhoundsk.tw@gmail.com> Link: https://lore.kernel.org/r/20240609173728.2950808-1-foxhoundsk.tw@gmail.com Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-14Documentation: gpio: clarify sysfs line values are logicalKent Gibson
Clarify that line values are logical, not physical, by replacing high/low terminology with active/inactive. Signed-off-by: Kent Gibson <warthog618@gmail.com> Reviewed-by: Andy Shevchenko <amdy.shevchenko@gmail.com> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-22Documentation: gpio: update sysfs documentation to reference new chardev docKent Gibson
Update GPIO sysfs interface documentation to reference the new chardev document rather than gpio.h. Signed-off-by: Kent Gibson <warthog618@gmail.com> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-22Documentation: gpio: move sysfs into an obsolete sectionKent Gibson
The GPIO sysfs API is long obsolete, so highlight this even further by moving it into an obsolete APIs section in both the admin-guide and userspace-api books. Signed-off-by: Kent Gibson <warthog618@gmail.com> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>