On Tue, Jun 4, 2013 at 12:51 PM, Arnd Bergmann [off-list ref] wrote:

On Tuesday 04 June 2013, Rob Herring wrote:

quoted

On Sat, Jun 1, 2013 at 3:57 PM, Arnd Bergmann [off-list ref] wrote:

quoted

On Saturday 01 June 2013, Rob Herring wrote:

quoted

No, we still need empty functions. Here is what of_device.h looks like:

http://tinyurl.com/l2azz5m

BTW, it has your ack.

Could you add a patch on top that only puts the function declarations
inside of #ifdef that don't have an inline wrapper?

I'm confused. You mean that DO have an inline? Like this:

void foo(void);

#ifdef CONFIG_OF
void bar(void);
#else
static inline void bar(void) {}
#endif

Yes, sorry. That's what I meant.

quoted

quoted

It's really annoying to have to change the header file every time one
needs to call a function from a driver in the DT-only case.

The functions without inlines are ones that drivers should not call
and should only be called from OF enabled code. That's why we have not
done a complete pass of adding inlines for everything.

The problem is that it's a bad default. The convention in kernel code
is not to hide declarations in #ifdef, for multiple reasons:

* It avoids unnecessary code rebuilds when the symbol changes between
  two 'make' runs.

* It lets drivers and platform code call the function from dead code
  without causing a build error, thus improving compile coverage.

* It's much nicer to read when can write your code like

void __init exynos_init_io(struct map_desc *mach_desc, int size)
{
        if (IS_ENABLED_(CONFIG_OF) && initial_boot_params)
                of_scan_flat_dt(exynos_fdt_map_chipid, NULL);
        else
                iotable_init(exynos_iodesc, ARRAY_SIZE(exynos_iodesc));
        ...
}

instead of

void __init exynos_init_io(struct map_desc *mach_desc, int size)
{
#ifdef CONFIG_OF
        if (initial_boot_params)
                of_scan_flat_dt(exynos_fdt_map_chipid, NULL);
        else
#endif
                iotable_init(exynos_iodesc, ARRAY_SIZE(exynos_iodesc));
        ...
}

The first one looks like actual C code, the second is really ugly,
and an inline wrapper wouldn't even do the right thing here.

Right. I get all that. You still have to go add inlines if you want to make:

if (IS_ENABLED(CONFIG_OF))
    of_foo();

just be:

of_foo();

There are situations for both and only inlines cover both cases. I
don't see a reason we would want to allow the first case and not allow
the second case. I am tired of taking patches adding the inlines 1 by
1, so perhaps we need to refactor the OF headers to better separate
core infrastructure includes vs. driver only includes if that is
really a concern.

Rob