• Alexandre Courbot's avatar
    gpio: remove gpio_descs global array · 14e85c0e
    Alexandre Courbot authored
    Replace the ARCH_NR_GPIOS-sized static array of GPIO descriptors by
    dynamically-allocated arrays for each GPIO chip.
    
    This change makes gpio_to_desc() perform in O(n) (where n is the number
    of GPIO chips registered) instead of O(1), however since n is rarely
    bigger than 1 or 2 no noticeable performance issue is expected.
    Besides this provides more incentive for GPIO consumers to move to the
    gpiod interface. One could use a O(log(n)) structure to link the GPIO
    chips together, but considering the low limit of n the hypothetical
    performance benefit is probably not worth the added complexity.
    
    This patch uses kcalloc() in gpiochip_add(), which removes the ability
    to add a chip before kcalloc() can operate. I am not aware of such
    cases, but if someone bisects up to this patch then I will be proven
    wrong...
    Signed-off-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
    Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    14e85c0e
gpiolib.c 55.6 KB