Hi Sam, I love your patch! Perhaps something to improve: [auto build test WARNING on drm-intel/for-linux-next] [also build test WARNING on drm-exynos/exynos-drm-next tegra-drm/drm/tegra/for-next drm-tip/drm-tip linus/master v5.8-rc4 next-20200709] [cannot apply to drm/drm-next] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Sam-Ravnborg/drm-drm_fb_helper-f... base: git://anongit.freedesktop.org/drm-intel for-linux-next config: x86_64-randconfig-s021-20200709 (attached as .config) compiler: gcc-9 (Debian 9.3.0-14) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.2-37-gc9676a3b-dirty # save the attached .config to linux build tree make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) vim +386 drivers/gpu/drm/drm_fb_helper.c 373 374 static void drm_fb_helper_dirty_blit_real(struct drm_fb_helper *fb_helper, 375 struct drm_clip_rect *clip) 376 { 377 struct drm_framebuffer *fb = fb_helper->fb; 378 unsigned int cpp = fb->format->cpp[0]; 379 size_t offset = clip->y1 * fb->pitches[0] + clip->x1 * cpp; 380 void *src = fb_helper->fbdev->screen_buffer + offset; 381 void *dst = fb_helper->buffer->vaddr + offset; 382 size_t len = (clip->x2 - clip->x1) * cpp; 383 unsigned int y; 384 385 for (y = clip->y1; y < clip->y2; y++) { 387 src += fb->pitches[0]; 388 dst += fb->pitches[0]; 389 } 390 } 391 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org