Re: [Intel-gfx] [PATCH v11 3/4] drm/i915: Use new CRC debugfs API

[David Weinehall <tao@kernel.org>]

On Mon, Nov 14, 2016 at 12:44:25PM +0200, Jani Nikula wrote:
> On Thu, 06 Oct 2016, Tomeu Vizoso <tomeu.vizoso@collabora.com> wrote:
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 23a6c7213eca..7412a05fa5d9 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -14636,6 +14636,7 @@ static const struct drm_crtc_funcs intel_crtc_funcs = {
> >  	.page_flip = intel_crtc_page_flip,
> >  	.atomic_duplicate_state = intel_crtc_duplicate_state,
> >  	.atomic_destroy_state = intel_crtc_destroy_state,
> > +	.set_crc_source = intel_crtc_set_crc_source,
> >  };
> >  
> >  /**
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > index 737261b09110..31894b7c6517 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -1844,6 +1844,14 @@ void intel_color_load_luts(struct drm_crtc_state *crtc_state);
> >  /* intel_pipe_crc.c */
> >  int intel_pipe_crc_create(struct drm_minor *minor);
> >  void intel_pipe_crc_cleanup(struct drm_minor *minor);
> > +#ifdef CONFIG_DEBUG_FS
> > +int intel_crtc_set_crc_source(struct drm_crtc *crtc, const char *source_name,
> > +			      size_t *values_cnt);
> > +#else
> > +static inline int intel_crtc_set_crc_source(struct drm_crtc *crtc,
> > +					    const char *source_name,
> > +					    size_t *values_cnt) { return 0; }
> > +#endif
> 
> "inline" here doesn't work because it's used as a function pointer.
> 
> Is it better to have a function that returns 0 for .set_crc_source, or
> to set .set_crc_source to NULL when CONFIG_DEBUG_FS=n?

I'd say that whenever we have a function pointer we should have a dummy
function without side-effects for this kind of things.


Kind regards, David