Hi Gaurav,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on drm-intel/for-linux-next]
[cannot apply to v5.3-rc7 next-20190903]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Gaurav-K-Singh/drm-i915-Fix-corruption-lines-on-the-screen-on-Gen9-chromebooks/20190904-151433
base:   git://anongit.freedesktop.org/drm-intel for-linux-next
config: i386-defconfig (attached as .config)
compiler: gcc-7 (Debian 7.4.0-11) 7.4.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   drivers/gpu/drm/i915/display/intel_fbc.c: In function 'intel_fbc_enable':
>> drivers/gpu/drm/i915/display/intel_fbc.c:1100:8: error: implicit declaration of function 'IS_GEN9'; did you mean 'IS_GEN'? [-Werror=implicit-function-declaration]
       if (IS_GEN9(dev_priv))
           ^~~~~~~
           IS_GEN
   cc1: some warnings being treated as errors

vim +1100 drivers/gpu/drm/i915/display/intel_fbc.c

  1071	
  1072	/**
  1073	 * intel_fbc_enable: tries to enable FBC on the CRTC
  1074	 * @crtc: the CRTC
  1075	 * @crtc_state: corresponding &drm_crtc_state for @crtc
  1076	 * @plane_state: corresponding &drm_plane_state for the primary plane of @crtc
  1077	 *
  1078	 * This function checks if the given CRTC was chosen for FBC, then enables it if
  1079	 * possible. Notice that it doesn't activate FBC. It is valid to call
  1080	 * intel_fbc_enable multiple times for the same pipe without an
  1081	 * intel_fbc_disable in the middle, as long as it is deactivated.
  1082	 */
  1083	void intel_fbc_enable(struct intel_crtc *crtc,
  1084			      struct intel_crtc_state *crtc_state,
  1085			      struct intel_plane_state *plane_state)
  1086	{
  1087		struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
  1088		struct intel_fbc *fbc = &dev_priv->fbc;
  1089	
  1090		if (!fbc_supported(dev_priv))
  1091			return;
  1092	
  1093		mutex_lock(&fbc->lock);
  1094	
  1095		if (fbc->enabled) {
  1096			WARN_ON(fbc->crtc == NULL);
  1097			if (fbc->crtc == crtc) {
  1098				WARN_ON(!crtc_state->enable_fbc);
  1099				WARN_ON(fbc->active);
> 1100				if (IS_GEN9(dev_priv))
  1101					intel_wait_for_vblank(dev_priv, crtc->pipe);
  1102			}
  1103			goto out;
  1104		}
  1105	
  1106		if (!crtc_state->enable_fbc)
  1107			goto out;
  1108	
  1109		WARN_ON(fbc->active);
  1110		WARN_ON(fbc->crtc != NULL);
  1111	
  1112		intel_fbc_update_state_cache(crtc, crtc_state, plane_state);
  1113		if (intel_fbc_alloc_cfb(crtc)) {
  1114			fbc->no_fbc_reason = "not enough stolen memory";
  1115			goto out;
  1116		}
  1117	
  1118		DRM_DEBUG_KMS("Enabling FBC on pipe %c\n", pipe_name(crtc->pipe));
  1119		fbc->no_fbc_reason = "FBC enabled but not active yet\n";
  1120	
  1121		fbc->enabled = true;
  1122		fbc->crtc = crtc;
  1123	out:
  1124		mutex_unlock(&fbc->lock);
  1125	}
  1126	

---
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