Re: [PATCH 15/15] mmc: host: sdhci-iproc: Tell the compiler that ACPI functions may not be used

[Scott Branden]

On 2020-07-02 1:13 p.m., Lee Jones wrote:
> On Thu, 02 Jul 2020, Scott Branden wrote:
>
> > Hi Lee,
> >
> > On 2020-07-01 5:47 a.m., Lee Jones wrote:
> > > ... as is the case when !CONFIG_ACPI.
> > >
> > > Fixes the following W=1 kernel build warning:
> > >
> > >    mmc/host/sdhci-iproc.c:297:36: warning: âsdhci_iproc_acpi_idsâ defined but not used [-Wunused-const-variable=]
> > >
> > > Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > > Cc: Ray Jui <rjui@xxxxxxxxxxxx>
> > > Cc: Scott Branden <sbranden@xxxxxxxxxxxx>
> > > Cc: bcm-kernel-feedback-list@xxxxxxxxxxxx
> > > Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
> > > ---
> > >    drivers/mmc/host/sdhci-iproc.c | 2 +-
> > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/mmc/host/sdhci-iproc.c b/drivers/mmc/host/sdhci-iproc.c
> > > index 225603148d7de..9c7d130205edd 100644
> > > --- a/drivers/mmc/host/sdhci-iproc.c
> > > +++ b/drivers/mmc/host/sdhci-iproc.c
> > > @@ -294,7 +294,7 @@ static const struct of_device_id sdhci_iproc_of_match[] = {
> > >    };
> > >    MODULE_DEVICE_TABLE(of, sdhci_iproc_of_match);
> > Would it better to compile this in if CONFIG_ACPI is defined instead?
> > #if CONFIG_ACPI
> Literally can't win.
>
>   https://lore.kernel.org/linux-arm-kernel/CAGb2v66Ws4WNPZbOYQvikKoozj_2WjzS-Jq-o2VxT77=k0vODw@xxxxxxxxxxxxxx/
>
> Damned if we do, damned if we don't. ;)
This is very minor in this one change here, but it's just more bloat of 
things that really should be compiled out if they're not used.
I don't understand why __maybe_unused would be preferred approach - 
unless it is not linked in when it is not used?
> > > -static const struct acpi_device_id sdhci_iproc_acpi_ids[] = {
> > > +static const struct acpi_device_id __maybe_unused sdhci_iproc_acpi_ids[] = {
> > >    	{ .id = "BRCM5871", .driver_data = (kernel_ulong_t)&iproc_cygnus_data },
> > >    	{ .id = "BRCM5872", .driver_data = (kernel_ulong_t)&iproc_data },
> > >    	{ /* sentinel */ }