• David Brownell's avatar
    [PATCH] gpio_direction_output() needs an initial value · 28735a72
    David Brownell authored
    
    
    It's been pointed out that output GPIOs should have an initial value, to
    avoid signal glitching ...  among other things, it can be some time before
    a driver is ready.  This patch corrects that oversight, fixing
    
     - documentation
     - platforms supporting the GPIO interface
     - users of that call (just one for now, others are pending)
    
    There's only one user of this call for now since most platforms are still
    using non-generic GPIO setup code, which in most cases already couples the
    initial value with its "set output mode" request.
    
    Note that most platforms are clear about the hardware letting the output
    value be set before the pin direction is changed, but the s3c241x docs are
    vague on that topic ...  so those chips might not avoid the glitches.
    Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
    Acked-by: default avatarAndrew Victor <andrew@sanpeople.com>
    Acked-by: default avatarMilan Svoboda <msvoboda@ra.rockwell.com>
    Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.co...
    28735a72
pio.c 8.29 KB