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Billy Tsai cf517fef60 pinctrl: aspeed: Force to disable the function's signal
When the driver want to disable the signal of the function, it doesn't
need to query the state of the mux function's signal on a pin. The
condition below will miss the disable of the signal:
Ball | Default | P0 Signal | P0 Expression               | Other
-----+---------+-----------+-----------------------------+----------
 E21   GPIOG0    SD2CLK      SCU4B4[16]=1 & SCU450[1]=1    GPIOG0
-----+---------+-----------+-----------------------------+----------
 B22   GPIOG1    SD2CMD      SCU4B4[17]=1 & SCU450[1]=1    GPIOG1
-----+---------+-----------+-----------------------------+----------
Assume the register status like below:
SCU4B4[16] == 1 & SCU4B4[17] == 1 & SCU450[1]==1
After the driver set the Ball E21 to the GPIOG0:
SCU4B4[16] == 0 & SCU4B4[17] == 1 & SCU450[1]==0
When the driver want to set the Ball B22 to the GPIOG1, the condition of
the SD2CMD will be false causing SCU4B4[17] not to be cleared.

Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
Acked-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://lore.kernel.org/r/20220818101839.28860-1-billy_tsai@aspeedtech.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
History 2022-08-31 14:14:31 +02:00
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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.