Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753211AbcKPMYs (ORCPT ); Wed, 16 Nov 2016 07:24:48 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:35065 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751980AbcKPMYq (ORCPT ); Wed, 16 Nov 2016 07:24:46 -0500 MIME-Version: 1.0 In-Reply-To: <87a8d12lmy.fsf@intel.com> 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> From: Tomeu Vizoso Date: Wed, 16 Nov 2016 13:24:24 +0100 X-Google-Sender-Auth: XLWokBSHBesHE31F6JGAYfx_75s Message-ID: Subject: Re: [Intel-gfx] [PATCH v11 3/4] drm/i915: Use new CRC debugfs API To: Jani Nikula Cc: David Weinehall , David Airlie , Intel Graphics Development , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Thierry Reding , Daniel Vetter Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2411 Lines: 51 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. Regards, Tomeu