bebff81fb8
Model the I2C bus clock divider as a part of the Core Clock Framework. Primarily this removes the clk_get_rate() call from each transfer. This call causes problems for slave drivers that themselves have internal clock components that are controlled by an I2C interface. When the slave's internal clock component is prepared, the prepare lock is obtained, and it makes calls to the I2C subsystem to command the hardware to activate the clock. In order to perform the I2C transfer, this driver sets the divider, which requires it to get the parent clock rate, which it does with clk_get_rate(). Unfortunately, this function will try to take the clock prepare lock, which is already held by the slave's internal clock calls creating a deadlock. Modeling the divider in the CCF natively removes this dependency and the divider value is only set upon changing the bus clock frequency or changes in the parent clock that cascade down to this divisor. This obviates the need to set the divider with every transfer and avoids the deadlock described above. It also should provide better clock debugging and save a few cycles on each transfer due to not having to recalcuate the divider value. Signed-off-by: Annaliese McDermond <nh6z@nh6z.net> Acked-by: Stefan Wahren <stefan.wahren@i2se.com> Reviewed-by: Eric Anholt <eric@anholt.net> Signed-off-by: Wolfram Sang <wsa@the-dreams.de> |
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
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 Restructured Text 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.