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Starting with the A83T SoC, Allwinner introduced a new timing mode for its MMC clocks. The new mode changes how the MMC controller sample and output clocks are delayed to match chip and board specifics. There are two controls for this, one on the CCU side controlling how the clocks behave, and one in the MMC controller controlling what inputs to take and how to route them. In the old mode, the MMC clock had 2 child clocks providing the output and sample clocks, which could be delayed by a number of clock cycles measured from the MMC clock's parent. With the new mode, the 2 delay clocks are no longer active. Instead, the delays and associated controls are moved into the MMC controller. The output of the MMC clock is also halved. The difference in how things are wired between the modes means that the clock controls and the MMC controls must match. To achieve this in a clear, explicit way, we introduce two functions for the MMC driver to use: one queries the hardware for the current mode set, and the other allows the MMC driver to request a mode. Signed-off-by: Chen-Yu Tsai <wens@csie.org> Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.