On Friday 08 February 2013, Hiroshi Doyu wrote:
> > > +#if defined(CONFIG_ARCH_TEGRA_3x_SOC)
> >
> > how about using:
> >
> > #if IS_BUILTIN(CONFIG_ARCH_TEGRA_3x_SOC)
> >
> > instead ?
>
> Why is IS_BUILTIN() prefered?
>
Inside of a function, if(IS_ENABLED(CONFIG_FOO)) or the respective IS_BUILTIN is
preferred over #ifdef because it provides better compile coverage and better
readability. Also, IS_ENABLED() is nice when you want to check if something
is builtin or module, without having to write a complex expression.
If you just replace the #ifdef with #if IS_BUILTIN as Felipe suggested, I see
no real benefit, but it would be nice to write this as
void __init tegra_hotplug_init(void)
{
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
return;
if (IS_ENABLED(CONFIG_ARCH_TEGRA_2x_SOC)) && tegra_chip_id == TEGRA20)
tegra_hotplug_shutdown = tegra20_hotplug_shutdown;
if (IS_ENABLED(CONFIG_ARCH_TEGRA_3x_SOC)) && tegra_chip_id == TEGRA30)
tegra_hotplug_shutdown = tegra30_hotplug_shutdown;
}
which completely avoids all preprocessor conditionals and replaces them
with compile-time choices based on constant expressions to eliminate the
code paths for disabled platforms.
Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-tegra" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
