[PATCH 2/2] 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.

After the prevous prep patch to use adjusted_mode->clock instead of
mode->clock the only thing left is to clean up things a bit. I've
opted to pass in an adjust_mode param to dp_adjust_dithering because
that way we can be sure to avoid duplicating this logic - which was
the cause behind a dp link bw calculation bug in the past.

Also mark the mode argument of pch_panel_fitting const.

v2: Split up the mode->clock => adjusted_mode->clock change,
as suggested by Chris Wilson.

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    |   12 ++++++------
 drivers/gpu/drm/i915/intel_drv.h   |    2 +-
 drivers/gpu/drm/i915/intel_panel.c |    2 +-
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index a9dffa6..c5c5669 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)
@@ -700,14 +700,14 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode,
 					mode, adjusted_mode);
 	}
 
-	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], adjusted_mode->clock);
 
-	if (!intel_dp_adjust_dithering(intel_dp, adjusted_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;
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