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Several camera sensor drivers access the "clock-frequency" property directly to retrieve the external clock rate, or modify the clock rate of the external clock programmatically. Both behaviours are valid on a subset of ACPI platforms, but are considered deprecated on OF platforms, and do not support ACPI platforms that implement MIPI DisCo for Imaging. Implementing them manually in drivers is deprecated, as that can encourage copying deprecated behaviour for OF platforms in new drivers, and lead to differences in behaviour between drivers. Instead, drivers that need to preserve the deprecated OF behaviour should use the devm_v4l2_sensor_clk_get_legacy() helper. This driver supports OF platforms only. The "clocks" and "clock-frequency" properties were initially mandatory in the DT bindings and were both set in the upstream DT sources. The driver retrieves the clock, retrieves and ignores the clock rate from the clock-frequency property, and sets the clock rate to a fixed value. This is deprecated behaviour for OF. Switch to using the devm_v4l2_sensor_clk_get_legacy() helper. This preserves setting the clock rate on OF platforms. Should support for OF platforms that set the clock rate through clock-frequency be considered unneeded in the future, the driver will only need to switch to devm_v4l2_sensor_clk_get() without any other change. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Reviewed-by: Mehdi Djait <mehdi.djait@linux.intel.com> Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
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.