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SubjectRe: [PATCH 8/9] gpiolib: use gpio_chips list in gpio_to_desc
On Sat, Feb 2, 2013 at 5:29 PM, Alexandre Courbot <> wrote:

> Parse the list of chips to find the descriptor corresponding to a GPIO
> number instead of directly picking the entry of the global gpio_desc[]
> array, which is due to be removed.
> This turns the complexity of converting a GPIO number into a descriptor
> from O(1) to O(n) where n is the number of GPIO chips in the system.
> Since n is ought to be small anyway, there should be no noticeable
> performance impact. Moreover, GPIO users who care for speed already have
> implemented their own gpio_get_value() and gpio_set_value() with a
> fast path for the GPIO numbers that matter and this change does not
> affect such use cases.
> The descriptor-based GPIO API, due to be introduced soon, will make this
> lookup unnecessary.
> Signed-off-by: Alexandre Courbot <>

OK it's a nice stepping stone.

Reviewed-by: Linus Walleij <>

Linus Walleij

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