Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932155AbcKPM6J (ORCPT ); Wed, 16 Nov 2016 07:58:09 -0500 Received: from mga07.intel.com ([134.134.136.100]:21483 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752755AbcKPM6G (ORCPT ); Wed, 16 Nov 2016 07:58:06 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,500,1473145200"; d="scan'208";a="787120164" From: Jani Nikula To: Tomeu Vizoso Cc: David Weinehall , David Airlie , Intel Graphics Development , "linux-kernel\@vger.kernel.org" , "dri-devel\@lists.freedesktop.org" , Thierry Reding , Daniel Vetter Subject: Re: [Intel-gfx] [PATCH v11 3/4] drm/i915: Use new CRC debugfs API In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <1475767268-14379-1-git-send-email-tomeu.vizoso@collabora.com> <1475767268-14379-4-git-send-email-tomeu.vizoso@collabora.com> <87inrq2vee.fsf@intel.com> <20161115071609.GI8202@suiko.acc.umu.se> <87a8d12lmy.fsf@intel.com> Date: Wed, 16 Nov 2016 14:58:03 +0200 Message-ID: <87h9771t0k.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2816 Lines: 63 On Wed, 16 Nov 2016, Tomeu Vizoso wrote: > On 15 November 2016 at 09:27, Jani Nikula wrote: >> On Tue, 15 Nov 2016, David Weinehall wrote: >>> On Mon, Nov 14, 2016 at 12:44:25PM +0200, Jani Nikula wrote: >>>> On Thu, 06 Oct 2016, Tomeu Vizoso 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. >> >> Whoever calls .set_crc_source could do smarter things depending on the >> hook not being there vs. just silently plunging on. > > In this specific case, when CONFIG_DEBUG_FS=n it doesn't make any > sense to call that callback, so I think we should have a dummy > implementation to avoid adding an ifdef to the .c. We don't want the ifdef to the .c file, but we could do #ifdef CONFIG_DEBUG_FS int intel_crtc_set_crc_source(struct drm_crtc *crtc, const char *source_name, size_t *values_cnt); #else #define intel_crtc_set_crc_source NULL #endif BR, Jani. -- Jani Nikula, Intel Open Source Technology Center