[PATCH] drm/i915: don't chnage the original mode in dp_mode_fixup

[Daniel Vetter]

We should only frob adjusted_mode. This is in preparation of
a massive patch by Laurent Pinchart to make the mode argument
const.

The only thing we actually touch is mode->clock, but only if
it's a panel. And in that case we also set adjusted_mode->clock
to the same value. All the generic code already uses the
adjusted_mode exclusively, so we only have to move the dp
link bw calculations over to that. This requires a small
changes so that the shared code with mode_valid doesn't
touch the mode argument.

Also mark the mode argument of pch_panel_fitting const.

Reported-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/intel_dp.c    |   19 +++++++------------
 drivers/gpu/drm/i915/intel_drv.h   |    2 +-
 drivers/gpu/drm/i915/intel_panel.c |    2 +-
 3 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 296cfc2..05c4748 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -222,7 +222,7 @@ intel_dp_max_data_rate(int max_link_clock, int max_lanes)
 static bool
 intel_dp_adjust_dithering(struct intel_dp *intel_dp,
 			  struct drm_display_mode *mode,
-			  struct drm_display_mode *adjusted_mode)
+			  bool adjust_mode)
 {
 	int max_link_clock = intel_dp_link_clock(intel_dp_max_link_bw(intel_dp));
 	int max_lanes = intel_dp_max_lane_count(intel_dp);
@@ -236,8 +236,8 @@ intel_dp_adjust_dithering(struct intel_dp *intel_dp,
 		if (mode_rate > max_rate)
 			return false;
 
-		if (adjusted_mode)
-			adjusted_mode->private_flags
+		if (adjust_mode)
+			mode->private_flags
 				|= INTEL_MODE_DP_FORCE_6BPC;
 
 		return true;
@@ -260,7 +260,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
 			return MODE_PANEL;
 	}
 
-	if (!intel_dp_adjust_dithering(intel_dp, mode, NULL))
+	if (!intel_dp_adjust_dithering(intel_dp, mode, false))
 		return MODE_CLOCK_HIGH;
 
 	if (mode->clock < 10000)
@@ -698,25 +698,20 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode,
 		intel_fixed_panel_mode(intel_dp->panel_fixed_mode, adjusted_mode);
 		intel_pch_panel_fitting(dev, DRM_MODE_SCALE_FULLSCREEN,
 					mode, adjusted_mode);
-		/*
-		 * the mode->clock is used to calculate the Data&Link M/N
-		 * of the pipe. For the eDP the fixed clock should be used.
-		 */
-		mode->clock = intel_dp->panel_fixed_mode->clock;
 	}
 
-	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
+	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
 		return false;
 
 	DRM_DEBUG_KMS("DP link computation with max lane count %i "
 		      "max bw %02x pixel clock %iKHz\n",
 		      max_lane_count, bws[max_clock], mode->clock);
 
-	if (!intel_dp_adjust_dithering(intel_dp, mode, adjusted_mode))
+	if (!intel_dp_adjust_dithering(intel_dp, adjusted_mode, true))
 		return false;
 
 	bpp = adjusted_mode->private_flags & INTEL_MODE_DP_FORCE_6BPC ? 18 : 24;
-	mode_rate = intel_dp_link_required(mode->clock, bpp);
+	mode_rate = intel_dp_link_required(adjusted_mode->clock, bpp);
 
 	for (lane_count = 1; lane_count <= max_lane_count; lane_count <<= 1) {
 		for (clock = 0; clock <= max_clock; clock++) {
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 3e09188..3e3b60c 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -372,7 +372,7 @@ extern void intel_fixed_panel_mode(struct drm_display_mode *fixed_mode,
 				   struct drm_display_mode *adjusted_mode);
 extern void intel_pch_panel_fitting(struct drm_device *dev,
 				    int fitting_mode,
-				    struct drm_display_mode *mode,
+				    const struct drm_display_mode *mode,
 				    struct drm_display_mode *adjusted_mode);
 extern u32 intel_panel_get_max_backlight(struct drm_device *dev);
 extern u32 intel_panel_get_backlight(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 2a1625d..7180cc8 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -56,7 +56,7 @@ intel_fixed_panel_mode(struct drm_display_mode *fixed_mode,
 void
 intel_pch_panel_fitting(struct drm_device *dev,
 			int fitting_mode,
-			struct drm_display_mode *mode,
+			const struct drm_display_mode *mode,
 			struct drm_display_mode *adjusted_mode)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-- 
1.7.10