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Date:   Tue, 6 Sep 2022 09:25:27 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     kernel test robot <lkp@intel.com>
Cc:     Arun R Murthy <arun.r.murthy@intel.com>, llvm@lists.linux.dev,
        kbuild-all@lists.01.org, linux-kernel@vger.kernel.org
Subject: Re: drivers/gpu/drm/i915/display/intel_display.c:7539:3: warning:
 unannotated fall-through between switch labels
Message-ID: <Yxd0d2EagFOhXe83@dev-arch.thelio-3990X>
References: <202209061654.YJExKpEK-lkp@intel.com>
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In-Reply-To: <202209061654.YJExKpEK-lkp@intel.com>
Precedence: bulk

On Tue, Sep 06, 2022 at 04:28:30PM +0800, kernel test robot wrote:
> tree:   https://github.com/intel-lab-lkp/linux/commits/UPDATE-20220906-121942/Arun-R-Murthy/drm-i915-Support-Async-Flip-on-Linear-buffers/20220426-200801
> head:   1e44191e6045780c15f33c16961af128c076bd4c
> commit: 1e44191e6045780c15f33c16961af128c076bd4c drm/i915: Support Async Flip on Linear buffers
> date:   4 hours ago
> config: i386-randconfig-a004
> compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://github.com/intel-lab-lkp/linux/commit/1e44191e6045780c15f33c16961af128c076bd4c
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review UPDATE-20220906-121942/Arun-R-Murthy/drm-i915-Support-Async-Flip-on-Linear-buffers/20220426-200801
>         git checkout 1e44191e6045780c15f33c16961af128c076bd4c
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/gpu/drm/i915/
> 
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All warnings (new ones prefixed by >>):
> 
> >> drivers/gpu/drm/i915/display/intel_display.c:7539:3: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
>                    case I915_FORMAT_MOD_X_TILED:
>                    ^
>    drivers/gpu/drm/i915/display/intel_display.c:7539:3: note: insert 'break;' to avoid fall-through
>                    case I915_FORMAT_MOD_X_TILED:
>                    ^
>                    break; 
>    1 warning generated.
> 
> 
> vim +7539 drivers/gpu/drm/i915/display/intel_display.c
> 
> b0b2bed2a1305c Ville Syrj?l?         2022-02-14  7458  
> b0b2bed2a1305c Ville Syrj?l?         2022-02-14  7459  static int intel_async_flip_check_hw(struct intel_atomic_state *state, struct intel_crtc *crtc)
> 30ff93af9e19db Karthik B S           2020-09-21  7460  {
> 30ff93af9e19db Karthik B S           2020-09-21  7461  	struct drm_i915_private *i915 = to_i915(state->base.dev);
> 30ff93af9e19db Karthik B S           2020-09-21  7462  	const struct intel_crtc_state *old_crtc_state, *new_crtc_state;
> 30ff93af9e19db Karthik B S           2020-09-21  7463  	const struct intel_plane_state *new_plane_state, *old_plane_state;
> 30ff93af9e19db Karthik B S           2020-09-21  7464  	struct intel_plane *plane;
> 30ff93af9e19db Karthik B S           2020-09-21  7465  	int i;
> 30ff93af9e19db Karthik B S           2020-09-21  7466  
> 0826edb6a5e5b3 Jos? Roberto de Souza 2021-10-29  7467  	old_crtc_state = intel_atomic_get_old_crtc_state(state, crtc);
> 0826edb6a5e5b3 Jos? Roberto de Souza 2021-10-29  7468  	new_crtc_state = intel_atomic_get_new_crtc_state(state, crtc);
> 0826edb6a5e5b3 Jos? Roberto de Souza 2021-10-29  7469  
> b0b2bed2a1305c Ville Syrj?l?         2022-02-14  7470  	if (!new_crtc_state->uapi.async_flip)
> b0b2bed2a1305c Ville Syrj?l?         2022-02-14  7471  		return 0;
> b0b2bed2a1305c Ville Syrj?l?         2022-02-14  7472  
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7473  	if (!new_crtc_state->hw.active) {
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7474  		drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7475  			    "[CRTC:%d:%s] not active\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7476  			    crtc->base.base.id, crtc->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7477  		return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7478  	}
> 30ff93af9e19db Karthik B S           2020-09-21  7479  
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7480  	if (intel_crtc_needs_modeset(new_crtc_state)) {
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7481  		drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7482  			    "[CRTC:%d:%s] modeset required\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7483  			    crtc->base.base.id, crtc->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7484  		return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7485  	}
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7486  
> 30ff93af9e19db Karthik B S           2020-09-21  7487  	if (old_crtc_state->active_planes != new_crtc_state->active_planes) {
> 30ff93af9e19db Karthik B S           2020-09-21  7488  		drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7489  			    "[CRTC:%d:%s] Active planes cannot be in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7490  			    crtc->base.base.id, crtc->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7491  		return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7492  	}
> 30ff93af9e19db Karthik B S           2020-09-21  7493  
> 30ff93af9e19db Karthik B S           2020-09-21  7494  	for_each_oldnew_intel_plane_in_state(state, plane, old_plane_state,
> 30ff93af9e19db Karthik B S           2020-09-21  7495  					     new_plane_state, i) {
> 0826edb6a5e5b3 Jos? Roberto de Souza 2021-10-29  7496  		if (plane->pipe != crtc->pipe)
> 0826edb6a5e5b3 Jos? Roberto de Souza 2021-10-29  7497  			continue;
> 0826edb6a5e5b3 Jos? Roberto de Souza 2021-10-29  7498  
> 30ff93af9e19db Karthik B S           2020-09-21  7499  		/*
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7500  		 * Only async flip capable planes should be in the state
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7501  		 * if we're really about to ask the hardware to perform
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7502  		 * an async flip. We should never get this far otherwise.
> 30ff93af9e19db Karthik B S           2020-09-21  7503  		 */
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7504  		if (drm_WARN_ON(&i915->drm,
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7505  				new_crtc_state->do_async_flip && !plane->async_flip))
> 30ff93af9e19db Karthik B S           2020-09-21  7506  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7507  
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7508  		/*
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7509  		 * Only check async flip capable planes other planes
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7510  		 * may be involved in the initial commit due to
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7511  		 * the wm0/ddb optimization.
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7512  		 *
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7513  		 * TODO maybe should track which planes actually
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7514  		 * were requested to do the async flip...
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7515  		 */
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7516  		if (!plane->async_flip)
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7517  			continue;
> 2e08437160d1e8 Ville Syrj?l?         2022-02-14  7518  
> 30ff93af9e19db Karthik B S           2020-09-21  7519  		/*
> 30ff93af9e19db Karthik B S           2020-09-21  7520  		 * FIXME: This check is kept generic for all platforms.
> 244dba4cb59637 Lucas De Marchi       2021-07-28  7521  		 * Need to verify this for all gen9 platforms to enable
> 30ff93af9e19db Karthik B S           2020-09-21  7522  		 * this selectively if required.
> 30ff93af9e19db Karthik B S           2020-09-21  7523  		 */
> 30ff93af9e19db Karthik B S           2020-09-21  7524  		switch (new_plane_state->hw.fb->modifier) {
> 1e44191e604578 Arun R Murthy         2022-09-06  7525  		case DRM_FORMAT_MOD_LINEAR:
> 1e44191e604578 Arun R Murthy         2022-09-06  7526  			/*
> 1e44191e604578 Arun R Murthy         2022-09-06  7527  			 * FIXME: Async on Linear buffer is supported on ICL as
> 1e44191e604578 Arun R Murthy         2022-09-06  7528  			 * but with additional alignment and fbc restrictions
> 1e44191e604578 Arun R Murthy         2022-09-06  7529  			 * need to be taken care of. These aren't applicable for
> 1e44191e604578 Arun R Murthy         2022-09-06  7530  			 * gen12+.
> 1e44191e604578 Arun R Murthy         2022-09-06  7531  			 */
> 1e44191e604578 Arun R Murthy         2022-09-06  7532  			if (DISPLAY_VER(i915) < 12) {
> 1e44191e604578 Arun R Murthy         2022-09-06  7533  				drm_dbg_kms(&i915->drm,
> 1e44191e604578 Arun R Murthy         2022-09-06  7534  					    "[PLANE:%d:%s] Modifier does not support async flips\n",
> 1e44191e604578 Arun R Murthy         2022-09-06  7535  					    plane->base.base.id, plane->base.name);
> 1e44191e604578 Arun R Murthy         2022-09-06  7536  				return -EINVAL;
> 1e44191e604578 Arun R Murthy         2022-09-06  7537  			}

This new case statement should have an explicit 'break' at the end per
Documentation/process/deprecated.rst:

  All switch/case blocks must end in one of:

  * break;
  * fallthrough;
  * continue;
  * goto <label>;
  * return [expression];

GCC allows more implicit fallthroughs than clang does: https://godbolt.org/z/vWvKnqn8E

Cheers,
Nathan

> 30ff93af9e19db Karthik B S           2020-09-21 @7539  		case I915_FORMAT_MOD_X_TILED:
> 30ff93af9e19db Karthik B S           2020-09-21  7540  		case I915_FORMAT_MOD_Y_TILED:
> 30ff93af9e19db Karthik B S           2020-09-21  7541  		case I915_FORMAT_MOD_Yf_TILED:
> 072ce4164f973b Stanislav Lisovskiy   2022-01-18  7542  		case I915_FORMAT_MOD_4_TILED:
> 30ff93af9e19db Karthik B S           2020-09-21  7543  			break;
> 30ff93af9e19db Karthik B S           2020-09-21  7544  		default:
> 30ff93af9e19db Karthik B S           2020-09-21  7545  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7546  				    "[PLANE:%d:%s] Modifier does not support async flips\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7547  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7548  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7549  		}
> 30ff93af9e19db Karthik B S           2020-09-21  7550  
> aaec72ee90bccc Ville Syrj?l?         2021-10-18  7551  		if (new_plane_state->hw.fb->format->num_planes > 1) {
> aaec72ee90bccc Ville Syrj?l?         2021-10-18  7552  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7553  				    "[PLANE:%d:%s] Planar formats do not support async flips\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7554  				    plane->base.base.id, plane->base.name);
> aaec72ee90bccc Ville Syrj?l?         2021-10-18  7555  			return -EINVAL;
> aaec72ee90bccc Ville Syrj?l?         2021-10-18  7556  		}
> aaec72ee90bccc Ville Syrj?l?         2021-10-18  7557  
> be6c1dd5ac074d Imre Deak             2021-10-27  7558  		if (old_plane_state->view.color_plane[0].mapping_stride !=
> be6c1dd5ac074d Imre Deak             2021-10-27  7559  		    new_plane_state->view.color_plane[0].mapping_stride) {
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7560  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7561  				    "[PLANE:%d:%s] Stride cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7562  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7563  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7564  		}
> 30ff93af9e19db Karthik B S           2020-09-21  7565  
> 30ff93af9e19db Karthik B S           2020-09-21  7566  		if (old_plane_state->hw.fb->modifier !=
> 30ff93af9e19db Karthik B S           2020-09-21  7567  		    new_plane_state->hw.fb->modifier) {
> 30ff93af9e19db Karthik B S           2020-09-21  7568  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7569  				    "[PLANE:%d:%s] Modifier cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7570  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7571  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7572  		}
> 30ff93af9e19db Karthik B S           2020-09-21  7573  
> 30ff93af9e19db Karthik B S           2020-09-21  7574  		if (old_plane_state->hw.fb->format !=
> 30ff93af9e19db Karthik B S           2020-09-21  7575  		    new_plane_state->hw.fb->format) {
> 30ff93af9e19db Karthik B S           2020-09-21  7576  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7577  				    "[PLANE:%d:%s] Pixel format cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7578  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7579  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7580  		}
> 30ff93af9e19db Karthik B S           2020-09-21  7581  
> 30ff93af9e19db Karthik B S           2020-09-21  7582  		if (old_plane_state->hw.rotation !=
> 30ff93af9e19db Karthik B S           2020-09-21  7583  		    new_plane_state->hw.rotation) {
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7584  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7585  				    "[PLANE:%d:%s] Rotation cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7586  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7587  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7588  		}
> 30ff93af9e19db Karthik B S           2020-09-21  7589  
> 30ff93af9e19db Karthik B S           2020-09-21  7590  		if (!drm_rect_equals(&old_plane_state->uapi.src, &new_plane_state->uapi.src) ||
> 30ff93af9e19db Karthik B S           2020-09-21  7591  		    !drm_rect_equals(&old_plane_state->uapi.dst, &new_plane_state->uapi.dst)) {
> 30ff93af9e19db Karthik B S           2020-09-21  7592  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7593  				    "[PLANE:%d:%s] Size/co-ordinates cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7594  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7595  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7596  		}
> 30ff93af9e19db Karthik B S           2020-09-21  7597  
> 30ff93af9e19db Karthik B S           2020-09-21  7598  		if (old_plane_state->hw.alpha != new_plane_state->hw.alpha) {
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7599  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7600  				    "[PLANES:%d:%s] Alpha value cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7601  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7602  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7603  		}
> 30ff93af9e19db Karthik B S           2020-09-21  7604  
> 30ff93af9e19db Karthik B S           2020-09-21  7605  		if (old_plane_state->hw.pixel_blend_mode !=
> 30ff93af9e19db Karthik B S           2020-09-21  7606  		    new_plane_state->hw.pixel_blend_mode) {
> 30ff93af9e19db Karthik B S           2020-09-21  7607  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7608  				    "[PLANE:%d:%s] Pixel blend mode cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7609  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7610  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7611  		}
> 30ff93af9e19db Karthik B S           2020-09-21  7612  
> 30ff93af9e19db Karthik B S           2020-09-21  7613  		if (old_plane_state->hw.color_encoding != new_plane_state->hw.color_encoding) {
> 30ff93af9e19db Karthik B S           2020-09-21  7614  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7615  				    "[PLANE:%d:%s] Color encoding cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7616  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7617  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7618  		}
> 30ff93af9e19db Karthik B S           2020-09-21  7619  
> 30ff93af9e19db Karthik B S           2020-09-21  7620  		if (old_plane_state->hw.color_range != new_plane_state->hw.color_range) {
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7621  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7622  				    "[PLANE:%d:%s] Color range cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7623  				    plane->base.base.id, plane->base.name);
> 30ff93af9e19db Karthik B S           2020-09-21  7624  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7625  		}
> ef6ba31dd38405 Anshuman Gupta        2021-09-24  7626  
> ef6ba31dd38405 Anshuman Gupta        2021-09-24  7627  		/* plane decryption is allow to change only in synchronous flips */
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7628  		if (old_plane_state->decrypt != new_plane_state->decrypt) {
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7629  			drm_dbg_kms(&i915->drm,
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7630  				    "[PLANE:%d:%s] Decryption cannot be changed in async flip\n",
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7631  				    plane->base.base.id, plane->base.name);
> ef6ba31dd38405 Anshuman Gupta        2021-09-24  7632  			return -EINVAL;
> 30ff93af9e19db Karthik B S           2020-09-21  7633  		}
> 6b4e414ce8dab7 Ville Syrj?l?         2022-02-14  7634  	}
> 30ff93af9e19db Karthik B S           2020-09-21  7635  
> 30ff93af9e19db Karthik B S           2020-09-21  7636  	return 0;
> 30ff93af9e19db Karthik B S           2020-09-21  7637  }
> 30ff93af9e19db Karthik B S           2020-09-21  7638  
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://01.org/lkp