drm/i915: fix up adjusted_mode tracking for interlaced modes

With the hw state readout&check code it's important that the values we
keep around are the canonical ones. Unfortunately when adding the pipe
timings readout support I've missed that the write side adjusts the
timings in the pipe config.

Fix this up and so prevent the unsightly WARN noise in dmesg. This
regression has been introduced in

commit 1bd1bd80
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Mon Apr 29 21:56:12 2013 +0200

    drm/i915: hw state readout support for pipe timings
Reported-by: Paulo Zanoni <przanoni@gmail.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -4675,12 +4675,17 @@ static void intel_set_pipe_timings(struct intel_crtc *intel_crtc,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	enum pipe pipe = intel_crtc->pipe;
 	enum transcoder cpu_transcoder = intel_crtc->config.cpu_transcoder;
-	uint32_t vsyncshift;
+	uint32_t vsyncshift, crtc_vtotal, crtc_vblank_end;
+
+	/* We need to be careful not to changed the adjusted mode, for otherwise
+	 * the hw state checker will get angry at the mismatch. */
+	crtc_vtotal = adjusted_mode->crtc_vtotal;
+	crtc_vblank_end = adjusted_mode->crtc_vblank_end;
 
 	if (!IS_GEN2(dev) && adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE) {
 		/* the chip adds 2 halflines automatically */
-		adjusted_mode->crtc_vtotal -= 1;
-		adjusted_mode->crtc_vblank_end -= 1;
+		crtc_vtotal -= 1;
+		crtc_vblank_end -= 1;
 		vsyncshift = adjusted_mode->crtc_hsync_start
 			     - adjusted_mode->crtc_htotal / 2;
 	} else {
@@ -4702,10 +4707,10 @@ static void intel_set_pipe_timings(struct intel_crtc *intel_crtc,
 
 	I915_WRITE(VTOTAL(cpu_transcoder),
 		   (adjusted_mode->crtc_vdisplay - 1) |
-		   ((adjusted_mode->crtc_vtotal - 1) << 16));
+		   ((crtc_vtotal - 1) << 16));
 	I915_WRITE(VBLANK(cpu_transcoder),
 		   (adjusted_mode->crtc_vblank_start - 1) |
-		   ((adjusted_mode->crtc_vblank_end - 1) << 16));
+		   ((crtc_vblank_end - 1) << 16));
 	I915_WRITE(VSYNC(cpu_transcoder),
 		   (adjusted_mode->crtc_vsync_start - 1) |
 		   ((adjusted_mode->crtc_vsync_end - 1) << 16));