Re: [PATCH 1/1] drm/display: Fix building with GCC 15

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Oct 02, 2024 at 11:26:10AM +0300, Jani Nikula wrote:
> On Tue, 01 Oct 2024, Brahmajit Das <brahmajit.xyz@gmail.com> wrote:
> > GCC 15 enables -Werror=unterminated-string-initialization by default.
> > This results in the following build error
> >
> > drivers/gpu/drm/display/drm_dp_dual_mode_helper.c: In function ‘is_hdmi_adaptor’:
> > drivers/gpu/drm/display/drm_dp_dual_mode_helper.c:164:17: error: initializer-string for array of
> >  ‘char’ is too long [-Werror=unterminated-string-initialization]
> >   164 |                 "DP-HDMI ADAPTOR\x04";
> >       |                 ^~~~~~~~~~~~~~~~~~~~~
> >
> > After discussion with Ville, the fix was to increase the size of
> > dp_dual_mode_hdmi_id array by one, so that it can accommodate the new
> > line character. This should let us build the kernel with GCC 15.
> 
> Should be terminating NUL, not new line.
> 
> >
> > Signed-off-by: Brahmajit Das <brahmajit.xyz@gmail.com>
> > ---
> >  drivers/gpu/drm/display/drm_dp_dual_mode_helper.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/display/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/display/drm_dp_dual_mode_helper.c
> > index 14a2a8473682..295375868db6 100644
> > --- a/drivers/gpu/drm/display/drm_dp_dual_mode_helper.c
> > +++ b/drivers/gpu/drm/display/drm_dp_dual_mode_helper.c
> > @@ -160,11 +160,12 @@ EXPORT_SYMBOL(drm_dp_dual_mode_write);
> >  
> >  static bool is_hdmi_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN])
> >  {
> > -	static const char dp_dual_mode_hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] =
> > +	//+1 to avaoid spurious -Werror=unterminated-string-initialization warning
> 
> If we added comments for every little thing like this, there'd be more
> comments than code. ;)

I asked for a comment, otherwise I suspect I''d end up undoing this
after forgetting why it's there. OTOH maybe I'll get the "broken"
gcc upgrade before I look at this code again, which would solve
that particular problem.

> 
> > +	static const char dp_dual_mode_hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN + 1] =
> >  		"DP-HDMI ADAPTOR\x04";
> >  
> >  	return memcmp(hdmi_id, dp_dual_mode_hdmi_id,
> > -		      sizeof(dp_dual_mode_hdmi_id)) == 0;
> > +		      DP_DUAL_MODE_HDMI_ID_LEN) == 0;
> >  }
> >  
> >  static bool is_type1_adaptor(uint8_t adaptor_id)
> 
> -- 
> Jani Nikula, Intel

-- 
Ville Syrjälä
Intel