From mboxrd@z Thu Jan 1 00:00:00 1970 From: linus.walleij@linaro.org (Linus Walleij) Date: Tue, 5 Feb 2013 19:01:34 +0100 Subject: [PATCH 8/9] gpiolib: use gpio_chips list in gpio_to_desc In-Reply-To: <1359822572-26009-10-git-send-email-acourbot@nvidia.com> References: <1359822572-26009-1-git-send-email-acourbot@nvidia.com> <1359822572-26009-10-git-send-email-acourbot@nvidia.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 Yours, Linus Walleij