Re: [PATCH] drm/i915/pfit: Prevent negative coordinates in center mode

[kernel test robot <lkp@intel.com>]

Hi Nemesa,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-i915/for-linux-next]
[also build test WARNING on drm-i915/for-linux-next-fixes drm-tip/drm-tip linus/master v7.0-rc6 next-20260401]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Nemesa-Garg/drm-i915-pfit-Prevent-negative-coordinates-in-center-mode/20260403-100828
base:   https://gitlab.freedesktop.org/drm/i915/kernel.git for-linux-next
patch link:    https://lore.kernel.org/r/20260331181656.77300-1-nemesa.garg%40intel.com
patch subject: [PATCH] drm/i915/pfit: Prevent negative coordinates in center mode
config: loongarch-allmodconfig (https://download.01.org/0day-ci/archive/20260403/202604032320.Bmwm7fST-lkp@intel.com/config)
compiler: clang version 19.1.7 (https://github.com/llvm/llvm-project cd708029e0b2869e80abe31ddb175f7c35361f90)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260403/202604032320.Bmwm7fST-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202604032320.Bmwm7fST-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/i915/display/intel_pfit.c:209:9: warning: variable 'width' is uninitialized when used here [-Wuninitialized]
     209 |                                     width, height,
         |                                     ^~~~~
   include/drm/drm_print.h:653:52: note: expanded from macro 'drm_dbg_kms'
     653 |         drm_dev_dbg(__drm_to_dev(drm), DRM_UT_KMS, fmt, ##__VA_ARGS__)
         |                                                           ^~~~~~~~~~~
   include/drm/drm_print.h:563:39: note: expanded from macro 'drm_dev_dbg'
     563 |         __drm_dev_dbg(NULL, dev, cat, fmt, ##__VA_ARGS__)
         |                                              ^~~~~~~~~~~
   drivers/gpu/drm/i915/display/intel_pfit.c:194:22: note: initialize the variable 'width' to silence this warning
     194 |         int ret, x, y, width, height;
         |                             ^
         |                              = 0
>> drivers/gpu/drm/i915/display/intel_pfit.c:209:16: warning: variable 'height' is uninitialized when used here [-Wuninitialized]
     209 |                                     width, height,
         |                                            ^~~~~~
   include/drm/drm_print.h:653:52: note: expanded from macro 'drm_dbg_kms'
     653 |         drm_dev_dbg(__drm_to_dev(drm), DRM_UT_KMS, fmt, ##__VA_ARGS__)
         |                                                           ^~~~~~~~~~~
   include/drm/drm_print.h:563:39: note: expanded from macro 'drm_dev_dbg'
     563 |         __drm_dev_dbg(NULL, dev, cat, fmt, ##__VA_ARGS__)
         |                                              ^~~~~~~~~~~
   drivers/gpu/drm/i915/display/intel_pfit.c:194:30: note: initialize the variable 'height' to silence this warning
     194 |         int ret, x, y, width, height;
         |                                     ^
         |                                      = 0
   2 warnings generated.


vim +/width +209 drivers/gpu/drm/i915/display/intel_pfit.c

   183	
   184	/* adjusted_mode has been preset to be the panel's fixed mode */
   185	static int pch_panel_fitting(struct intel_crtc_state *crtc_state,
   186				     const struct drm_connector_state *conn_state)
   187	{
   188		struct intel_display *display = to_intel_display(crtc_state);
   189		struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
   190		const struct drm_display_mode *adjusted_mode =
   191			&crtc_state->hw.adjusted_mode;
   192		int pipe_src_w = drm_rect_width(&crtc_state->pipe_src);
   193		int pipe_src_h = drm_rect_height(&crtc_state->pipe_src);
   194		int ret, x, y, width, height;
   195	
   196		/* Native modes don't need fitting */
   197		if (adjusted_mode->crtc_hdisplay == pipe_src_w &&
   198		    adjusted_mode->crtc_vdisplay == pipe_src_h &&
   199		    crtc_state->output_format != INTEL_OUTPUT_FORMAT_YCBCR420)
   200			return 0;
   201	
   202		switch (conn_state->scaling_mode) {
   203		case DRM_MODE_SCALE_CENTER:
   204			if (adjusted_mode->crtc_hdisplay < pipe_src_w ||
   205			    adjusted_mode->crtc_vdisplay < pipe_src_h) {
   206				drm_dbg_kms(display->drm,
   207					    "[CRTC:%d:%s] pfit center mode source (%dx%d) exceeds display (%dx%d)\n",
   208					    crtc->base.base.id, crtc->base.name,
 > 209					    width, height,
   210					    adjusted_mode->crtc_hdisplay,
   211					    adjusted_mode->crtc_vdisplay);
   212				return -EINVAL;
   213			}
   214			width = pipe_src_w;
   215			height = pipe_src_h;
   216			x = (adjusted_mode->crtc_hdisplay - width + 1)/2;
   217			y = (adjusted_mode->crtc_vdisplay - height + 1)/2;
   218			break;
   219	
   220		case DRM_MODE_SCALE_ASPECT:
   221			/* Scale but preserve the aspect ratio */
   222			{
   223				u32 scaled_width = adjusted_mode->crtc_hdisplay * pipe_src_h;
   224				u32 scaled_height = pipe_src_w * adjusted_mode->crtc_vdisplay;
   225	
   226				if (scaled_width > scaled_height) { /* pillar */
   227					width = scaled_height / pipe_src_h;
   228					if (width & 1)
   229						width++;
   230					x = (adjusted_mode->crtc_hdisplay - width + 1) / 2;
   231					y = 0;
   232					height = adjusted_mode->crtc_vdisplay;
   233				} else if (scaled_width < scaled_height) { /* letter */
   234					height = scaled_width / pipe_src_w;
   235					if (height & 1)
   236						height++;
   237					y = (adjusted_mode->crtc_vdisplay - height + 1) / 2;
   238					x = 0;
   239					width = adjusted_mode->crtc_hdisplay;
   240				} else {
   241					x = y = 0;
   242					width = adjusted_mode->crtc_hdisplay;
   243					height = adjusted_mode->crtc_vdisplay;
   244				}
   245			}
   246			break;
   247	
   248		case DRM_MODE_SCALE_NONE:
   249			WARN_ON(adjusted_mode->crtc_hdisplay != pipe_src_w);
   250			WARN_ON(adjusted_mode->crtc_vdisplay != pipe_src_h);
   251			fallthrough;
   252		case DRM_MODE_SCALE_FULLSCREEN:
   253			x = y = 0;
   254			width = adjusted_mode->crtc_hdisplay;
   255			height = adjusted_mode->crtc_vdisplay;
   256			break;
   257	
   258		default:
   259			MISSING_CASE(conn_state->scaling_mode);
   260			return -EINVAL;
   261		}
   262	
   263		drm_rect_init(&crtc_state->pch_pfit.dst,
   264			      x, y, width, height);
   265		crtc_state->pch_pfit.enabled = true;
   266	
   267		/*
   268		 * SKL+ have unified scalers for pipes/planes so the
   269		 * checks are done in a single place for all scalers.
   270		 */
   271		if (DISPLAY_VER(display) >= 9)
   272			return 0;
   273	
   274		ret = intel_pch_pfit_check_dst_window(crtc_state);
   275		if (ret)
   276			return ret;
   277	
   278		ret = intel_pch_pfit_check_src_size(crtc_state);
   279		if (ret)
   280			return ret;
   281	
   282		ret = intel_pch_pfit_check_scaling(crtc_state);
   283		if (ret)
   284			return ret;
   285	
   286		ret = intel_pch_pfit_check_timings(crtc_state);
   287		if (ret)
   288			return ret;
   289	
   290		ret = intel_pch_pfit_check_cloning(crtc_state);
   291		if (ret)
   292			return ret;
   293	
   294		return 0;
   295	}
   296	

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