cf517fef60
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>
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.