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| author | Laura Abbott | 2018-05-21 19:57:07 +0200 |
|---|---|---|
| committer | Linus Walleij | 2018-05-23 14:01:03 +0200 |
| commit | 3027743f83f867d85662f5134e835c2e199cb9be (patch) | |
| tree | 9afbf1a13136d57191cb2a40c53dc4607c642b34 /drivers/gpio/Kconfig | |
| parent | gpio: aspeed: Use a cache of output data registers (diff) | |
| download | kernel-qcow2-linux-3027743f83f867d85662f5134e835c2e199cb9be.tar.gz kernel-qcow2-linux-3027743f83f867d85662f5134e835c2e199cb9be.tar.xz kernel-qcow2-linux-3027743f83f867d85662f5134e835c2e199cb9be.zip | |
gpio: Remove VLA from gpiolib
The new challenge is to remove VLAs from the kernel
(see https://lkml.org/lkml/2018/3/7/621) to eventually
turn on -Wvla.
Using a kmalloc array is the easy way to fix this but kmalloc is still
more expensive than stack allocation. Introduce a fast path with a
fixed size stack array to cover most chip with gpios below some fixed
amount. The slow path dynamically allocates an array to cover those
chips with a large number of gpios.
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Phil Reid <preid@electromag.com.au>
Reviewed-and-tested-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio/Kconfig')
| -rw-r--r-- | drivers/gpio/Kconfig | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index b960f6f35abd..71c0ab46f216 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -22,6 +22,18 @@ menuconfig GPIOLIB if GPIOLIB +config GPIOLIB_FASTPATH_LIMIT + int "Maximum number of GPIOs for fast path" + range 32 512 + default 512 + help + This adjusts the point at which certain APIs will switch from + using a stack allocated buffer to a dynamically allocated buffer. + + You shouldn't need to change this unless you really need to + optimize either stack space or performance. Change this carefully + since setting an incorrect value could cause stack corruption. + config OF_GPIO def_bool y depends on OF |