drm/exynos/decon5433: set STANDALONE_UPDATE_F also if planes are disabled

STANDALONE_UPDATE_F should be set if something changed in plane configurations,
including plane disable.
The patch fixes page-faults bugs, caused by decon still using framebuffers
of disabled planes.

v2: fixed clear-bit code (Thx Marek)
v3: use test_and_clear_bit (Thx Joonyoung)
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Tested-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos5433_drm_decon.c

@@ -46,7 +46,8 @@ enum decon_flag_bits {
 	BIT_CLKS_ENABLED,
 	BIT_IRQS_ENABLED,
 	BIT_WIN_UPDATED,
-	BIT_SUSPENDED
+	BIT_SUSPENDED,
+	BIT_REQUEST_UPDATE
 };
 
 struct decon_context {
@@ -313,6 +314,7 @@ static void decon_update_plane(struct exynos_drm_crtc *crtc,
 
 	/* window enable */
 	decon_set_bits(ctx, DECON_WINCONx(win), WINCONx_ENWIN_F, ~0);
+	set_bit(BIT_REQUEST_UPDATE, &ctx->flags);
 }
 
 static void decon_disable_plane(struct exynos_drm_crtc *crtc,
@@ -325,6 +327,7 @@ static void decon_disable_plane(struct exynos_drm_crtc *crtc,
 		return;
 
 	decon_set_bits(ctx, DECON_WINCONx(win), WINCONx_ENWIN_F, 0);
+	set_bit(BIT_REQUEST_UPDATE, &ctx->flags);
 }
 
 static void decon_atomic_flush(struct exynos_drm_crtc *crtc)
@@ -338,8 +341,7 @@ static void decon_atomic_flush(struct exynos_drm_crtc *crtc)
 	for (i = ctx->first_win; i < WINDOWS_NR; i++)
 		decon_shadow_protect_win(ctx, i, false);
 
-	/* update iff there are active windows */
-	if (crtc->base.state->plane_mask)
+	if (test_and_clear_bit(BIT_REQUEST_UPDATE, &ctx->flags))
 		decon_set_bits(ctx, DECON_UPDATE, STANDALONE_UPDATE_F, ~0);
 
 	if (ctx->out_type & IFTYPE_I80)