Re: [PATCH u-boot-marvell v2 8/9] arm: mvebu: spl: Use IS_ENABLED() instead of #ifdef where possible

Marek Behún
2021-12-14T09:45:30Z

On Tue, 14 Dec 2021 10:36:00 +0100
Pali Rohár <pali@kernel.org> wrote:

> On Friday 26 November 2021 15:37:37 Marek Behún wrote:
> > @@ -340,17 +333,17 @@ void board_init_f(ulong dummy)
> > timer_init();
> >
> > /* Armada 375 does not support SerDes and DDR3 init yet */
> > -#if !defined(CONFIG_ARMADA_375)
> > - /* First init the serdes PHY's */
> > - serdes_phy_config();
> > -
> > - /* Setup DDR */
> > - ret = ddr3_init();
> > - if (ret) {
> > - debug("ddr3_init() failed: %d\n", ret);
> > - hang();
> > + if (!IS_ENABLED(CONFIG_ARMADA_375)) {
> > + /* First init the serdes PHY's */
> > + serdes_phy_config();
> > +
> > + /* Setup DDR */
> > + ret = ddr3_init();
> > + if (ret) {
> > + debug("ddr3_init() failed: %d\n", ret);
> > + hang();
> > + }
> > }
> > -#endif
>
> As written in comment above there is no SerDes and DDR3 support for
> Armada 375 and therefore there is no serdes_phy_config() or ddr3_init()
> function. So this code needs not to be compiled at all and usage of
> #ifdef is correct here.

#ifdefs are almost never correct in C-files, for the parts of the code
they guard isn't put through syntactic analysis, and can therefore
contain bugs which we are not warned about.

Using if (IS_ENABLED()) almost never producess a different binary,
because the code is optimized away.

Marek