Re: warning in omap_connector

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Ville,

On Tue, Jun 30, 2020 at 05:39:02PM +0300, Ville Syrjälä wrote:
> On Tue, Jun 30, 2020 at 10:19:23AM -0400, Alex Deucher wrote:
> > On Tue, Jun 30, 2020 at 10:15 AM Ville Syrjälä wrote:
> > >
> > > On Tue, Jun 30, 2020 at 04:33:37PM +1000, Dave Airlie wrote:
> > > > Hey Laurent,
> > > >
> > > > I merged drm-misc-next and noticed this, I'm not sure if it's
> > > > collateral damage from something else changing or I've just missed it
> > > > previously. 32-bit arm build.
> > > >
> > > >
> > > > /home/airlied/devel/kernel/dim/src/drivers/gpu/drm/omapdrm/omap_connector.c:
> > > > In function ‘omap_connector_mode_valid’:
> > > > /home/airlied/devel/kernel/dim/src/drivers/gpu/drm/omapdrm/omap_connector.c:92:9:
> > > > warning: braces around scalar initializer
> > > >   struct drm_display_mode new_mode = { { 0 } };
> > >
> > > Probably fallout from my drm_display_mode shrinkage.
> > >
> > > Going to repeat my usual "just use {} when zero initializing
> > > structs" recommendation. Avoids these stupid warnings, and IMO
> > > also conveys the meaning better since there's no ambiguity
> > > between zero initializing the whole struct vs. zero initializing
> > > just the first member.
> > 
> > IIRC, LLVM and GCC treat these slightly differently.  We've generally
> > just moved to using memset to avoid different compiler complaints when
> > using these.
> 
> I don't particularly like memset() since the requirement to
> pass the size just adds another way to screw things up. The
> usual 'sizeof(*thing)' makes that slightly less of an issue,
> but I've noticed that people often don't use that.
> 
> Another issue with memset() is that you then can end up with
> a block of seemingly random collection of memsets()s between
> the variable declarations and the rest of the code. I suppose
> if we could declare variables anywhere we could always keep
> the two together so it wouldn't look so weird, but can't do
> that for the time being. And even with that it would still
> lead to less succinct code, which I generally dislike.

I'd prefer { } over memset, assuming clang and gcc would treat it
correctly. Ville, I can submit a patch, unless you want to do it
yourself as it's a fallout from drm_display_mode shrinkage ;-)
(seriously speaking, not pushing you, I just want to avoid duplicating
work).

-- 
Regards,

Laurent Pinchart
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