• Liu Gang's avatar
    powerpc/gpio: Fix the wrong GPIO input data on MPC8572/MPC8536 · 1aeef303
    Liu Gang authored
    For MPC8572/MPC8536, the status of GPIOs defined as output
    cannot be determined by reading GPDAT register, so the code
    use shadow data register instead. But the code may give the
    wrong status of GPIOs defined as input under some scenarios:
    
    1. If some pins were configured as inputs and were asserted
    high before booting the kernel, the shadow data has been
    initialized with those pin values.
    2. Some pins have been configured as output first and have
    been set to the high value, then reconfigured as input.
    
    The above cases will make the shadow data for those input
    pins to be set to high. Then reading the pin status will
    always return high even if the actual pin status is low.
    
    The code should eliminate the effects of the shadow data to
    the input pins, and the status of those pins should be
    read directly from GPDAT.
    
    Cc: stable@vger.kernel.org
    Acked-by: default avatarScott Wood <scottwood@freescale.com>
    Acked-by: default avatarAnatolij Gustschin <agust@denx.de>
    Signed-off-by: default avatarLiu Gang <Gang.Liu@freescale.com>
    Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    1aeef303
gpio-mpc8xxx.c 10 KB