Messages in this thread | | | From | Arnd Bergmann <> | Date | Sat, 30 Jul 2022 13:54:18 +0200 | Subject | Re: [PATCH] Allow configuration of ARCH_NR_GPIO |
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On Sat, Jul 30, 2022 at 2:38 AM Billie Alsup <balsup@cisco.com> wrote: > > From: Billie R Alsup <balsup@cisco.com> > > Problem: Some systems support a high number of GPIO pins. Allow > the kernel builder to configure the maximum number of pins, rather > than forcing a large value on everyone. > > Impact: Once a .config is generated, the ARCH_NR_GPIO setting > will persist. To return to a default setting, the CONFIG_ARCH_NR_GPIO > must be removed from .config file first. > > Trade-offs: It is possible to achieve similar via command line > parameters, e.g. > > make KBUILD_CFLAGS_KERNEL=-DARCH_NR_GPIOS=16384 > > to the build. This is problematic because the setting does not > show up in /proc/config.gz. It is also problematic for out-of-tree > module builds, which require similar if they invoke the API > gpio_is_valid(). In both cases, one could envision one system > working normally, and another failing, even though they both have > the same kernel version and /proc/config.gz. Therefore, it is > better to have the setting available in .config > > Signed-off-by: Billie R Alsup <balsup@cisco.com>
What is the use case for manually setting this rather than deriving it from the selected platforms?
Have you tried to use both a platform-specific option for the minimum number of this setting, and then restictricting the CONFIG_ARCH_NR_GPIO setting with a 'range' statement?
Arnd
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