drm/i915: Eliminate the ugly 'fb?:' constructs from the ilk/skl wm code

Don't access plane_state->fb until we know the plane to be visible.
It it's visible, it will have an fb, and thus we don't have to
consider the NULL fb case. Makes the code look nicer.

Cc: intel-gfx@lists.freedesktop.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1479498793-31021-25-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -1781,13 +1781,14 @@ static uint32_t ilk_compute_pri_wm(const struct intel_crtc_state *cstate,
 				   uint32_t mem_value,
 				   bool is_lp)
 {
-	int cpp = pstate->base.fb ?
-		drm_format_plane_cpp(pstate->base.fb->pixel_format, 0) : 0;
 	uint32_t method1, method2;
+	int cpp;
 
 	if (!cstate->base.active || !pstate->base.visible)
 		return 0;
 
+	cpp = drm_format_plane_cpp(pstate->base.fb->pixel_format, 0);
+
 	method1 = ilk_wm_method1(ilk_pipe_pixel_rate(cstate), cpp, mem_value);
 
 	if (!is_lp)
@@ -1809,13 +1810,14 @@ static uint32_t ilk_compute_spr_wm(const struct intel_crtc_state *cstate,
 				   const struct intel_plane_state *pstate,
 				   uint32_t mem_value)
 {
-	int cpp = pstate->base.fb ?
-		drm_format_plane_cpp(pstate->base.fb->pixel_format, 0) : 0;
 	uint32_t method1, method2;
+	int cpp;
 
 	if (!cstate->base.active || !pstate->base.visible)
 		return 0;
 
+	cpp = drm_format_plane_cpp(pstate->base.fb->pixel_format, 0);
+
 	method1 = ilk_wm_method1(ilk_pipe_pixel_rate(cstate), cpp, mem_value);
 	method2 = ilk_wm_method2(ilk_pipe_pixel_rate(cstate),
 				 cstate->base.adjusted_mode.crtc_htotal,
@@ -1853,12 +1855,13 @@ static uint32_t ilk_compute_fbc_wm(const struct intel_crtc_state *cstate,
 				   const struct intel_plane_state *pstate,
 				   uint32_t pri_val)
 {
-	int cpp = pstate->base.fb ?
-		drm_format_plane_cpp(pstate->base.fb->pixel_format, 0) : 0;
+	int cpp;
 
 	if (!cstate->base.active || !pstate->base.visible)
 		return 0;
 
+	cpp = drm_format_plane_cpp(pstate->base.fb->pixel_format, 0);
+
 	return ilk_wm_fbc(pri_val, drm_rect_width(&pstate->base.dst), cpp);
 }
 
@@ -3229,13 +3232,17 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
 			     int y)
 {
 	struct intel_plane_state *intel_pstate = to_intel_plane_state(pstate);
-	struct drm_framebuffer *fb = pstate->fb;
 	uint32_t down_scale_amount, data_rate;
 	uint32_t width = 0, height = 0;
-	unsigned format = fb ? fb->pixel_format : DRM_FORMAT_XRGB8888;
+	struct drm_framebuffer *fb;
+	u32 format;
 
 	if (!intel_pstate->base.visible)
 		return 0;
+
+	fb = pstate->fb;
+	format = fb->pixel_format;
+
 	if (pstate->plane->type == DRM_PLANE_TYPE_CURSOR)
 		return 0;
 	if (y && format != DRM_FORMAT_NV12)