[U-Boot] [PATCH 62/71] serial: spl: Implement empty functions for SPL

Marek Vasut
2012-09-18T18:03:17Z

Dear Scott Wood,

> On 09/18/2012 12:13:57 PM, Marek Vasut wrote:
> > Dear Tom Rini,
> >
> > > On Mon, Sep 17, 2012 at 01:21:27AM +0200, Marek Vasut wrote:
> > > > Implement empty serial_* functions for SPL without serial
> > > > support enabled. This is imperative to haave once serial
> > > > multi is enabled unconditionally.
> > > >
> > > > Signed-off-by: Marek Vasut <marex@denx.de>
> > > > Cc: Marek Vasut <marek.vasut@gmail.com>
> > > > Cc: Tom Rini <trini@ti.com>
> > > > ---
> > > >
> > > > common/serial.c | 12 ++++++++++++
> > > > 1 file changed, 12 insertions(+)
> > > >
> > > > diff --git a/common/serial.c b/common/serial.c
> > > > index 631af65..cef4ba8 100644
> > > > --- a/common/serial.c
> > > > +++ b/common/serial.c
> > > > @@ -27,6 +27,16 @@
> > > >
> > > > #include <post.h>
> > > > #include <linux/compiler.h>
> > > >
> > > > +/* Implement prototypes for SPL without serial support */
> > > > +#if defined(CONFIG_SPL_BUILD) &&
> >
> > !defined(CONFIG_SPL_SERIAL_SUPPORT)
> >
> > > > +int serial_init(void) { return 0; }
> > > > +void serial_setbrg(void) {}
> > > > +int serial_getc(void) { return 0; }
> > > > +int serial_tstc(void) { return 0; }
> > > > +void serial_putc(const char c) {}
> > > > +void serial_puts(const char *s) {}
> > >
> > > This isn't quite right. We need to allow for:
> > > - No output SPL, strings collected (so #defined to do{} while (0))
> >
> > Which is not type-checked and will drag in bugs.
>
> Not all that likely, since most code will either be built with printf
> enabled some of the time, or not contain printf (i.e. it's not quite
> the same situation as debug prints which may be rarely enabled).
>
> An inline function would be fine, but has to be done at the same place
> that normal printf is declared -- whereas a macro could be done after
> the fact. Unless you use a macro to redirect it to an inline function
> of a different name...
>
> I do not understand why you want to put these stubs in a C file instead
> of a header file, though -- you're preventing code from being optimized
> away, which is important in some SPLs.

I'd say the GCC must optimize it out anyway.

And if not, what solution do you suggest, move these into include/serial.h and
compile serial.c in conditionally?

> -Scott

Best regards,
Marek Vasut