drm/i915: Try to fix the messy IVB sprite scaling workaround

We now have a very clear method of disabling LP1+ wartermarks,
and we can actually detect if we actually did disable them, or
if they were already disabled. Use that to clean up the
WaCxSRDisabledForSpriteScaling:ivb handling.

I was hoping to apply the workaround in a way that wouldn't
require a blocking wait, but sadly IVB really does appear to
require LP1+ watermarks to be off for an entire frame before
enabling sprite scaling. Simply disabling LP1+ watermarks
during the previous frame is not enough, no matter how early
in the frame we do it :(

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b0a6e76..50da8a5 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1401,7 +1401,6 @@ typedef struct drm_i915_private {
 
        /* overlay */
        struct intel_overlay *overlay;
-       unsigned int sprite_scaling_enabled;
 
        /* backlight registers and fields in struct intel_panel */
        spinlock_t backlight_lock;

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7e02834..ecdb64e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2426,33 +2426,26 @@ static unsigned int ilk_compute_wm_dirty(struct drm_device *dev,
        return dirty;
 }
 
-/*
- * The spec says we shouldn't write when we don't need, because every write
- * causes WMs to be re-evaluated, expending some power.
- */
-static void hsw_write_wm_values(struct drm_i915_private *dev_priv,
-                               struct hsw_wm_values *results)
+static bool _ilk_disable_lp_wm(struct drm_i915_private *dev_priv,
+                              unsigned int dirty)
 {
-       struct drm_device *dev = dev_priv->dev;
        struct hsw_wm_values *previous = &dev_priv->wm.hw;
-       unsigned int dirty;
-       uint32_t val;
-
-       dirty = ilk_compute_wm_dirty(dev_priv->dev, previous, results);
-       if (!dirty)
-               return;
+       bool changed = false;
 
        if (dirty & WM_DIRTY_LP(3) && previous->wm_lp[2] & WM1_LP_SR_EN) {
                previous->wm_lp[2] &= ~WM1_LP_SR_EN;
                I915_WRITE(WM3_LP_ILK, previous->wm_lp[2]);
+               changed = true;
        }
        if (dirty & WM_DIRTY_LP(2) && previous->wm_lp[1] & WM1_LP_SR_EN) {
                previous->wm_lp[1] &= ~WM1_LP_SR_EN;
                I915_WRITE(WM2_LP_ILK, previous->wm_lp[1]);
+               changed = true;
        }
        if (dirty & WM_DIRTY_LP(1) && previous->wm_lp[0] & WM1_LP_SR_EN) {
                previous->wm_lp[0] &= ~WM1_LP_SR_EN;
                I915_WRITE(WM1_LP_ILK, previous->wm_lp[0]);
+               changed = true;
        }
 
        /*
@@ -2460,6 +2453,27 @@ static void hsw_write_wm_values(struct drm_i915_private *dev_priv,
         * Doing so could cause underruns.
         */
 
+       return changed;
+}
+
+/*
+ * The spec says we shouldn't write when we don't need, because every write
+ * causes WMs to be re-evaluated, expending some power.
+ */
+static void hsw_write_wm_values(struct drm_i915_private *dev_priv,
+                               struct hsw_wm_values *results)
+{
+       struct drm_device *dev = dev_priv->dev;
+       struct hsw_wm_values *previous = &dev_priv->wm.hw;
+       unsigned int dirty;
+       uint32_t val;
+
+       dirty = ilk_compute_wm_dirty(dev, previous, results);
+       if (!dirty)
+               return;
+
+       _ilk_disable_lp_wm(dev_priv, dirty);
+
        if (dirty & WM_DIRTY_PIPE(PIPE_A))
                I915_WRITE(WM0_PIPEA_ILK, results->wm_pipe[0]);
        if (dirty & WM_DIRTY_PIPE(PIPE_B))
@@ -2523,6 +2537,13 @@ static void hsw_write_wm_values(struct drm_i915_private *dev_priv,
        dev_priv->wm.hw = *results;
 }
 
+static bool ilk_disable_lp_wm(struct drm_device *dev)
+{
+       struct drm_i915_private *dev_priv = dev->dev_private;
+
+       return _ilk_disable_lp_wm(dev_priv, WM_DIRTY_LP_ALL);
+}
+
 static void haswell_update_wm(struct drm_crtc *crtc)
 {
        struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
@@ -2572,6 +2593,7 @@ static void haswell_update_sprite_wm(struct drm_plane *plane,
                                     uint32_t sprite_width, int pixel_size,
                                     bool enabled, bool scaled)
 {
+       struct drm_device *dev = plane->dev;
        struct intel_plane *intel_plane = to_intel_plane(plane);
 
        intel_plane->wm.enabled = enabled;
@@ -2579,6 +2601,16 @@ static void haswell_update_sprite_wm(struct drm_plane *plane,
        intel_plane->wm.horiz_pixels = sprite_width;
        intel_plane->wm.bytes_per_pixel = pixel_size;
 
+       /*
+        * IVB workaround: must disable low power watermarks for at least
+        * one frame before enabling scaling.  LP watermarks can be re-enabled
+        * when scaling is disabled.
+        *
+        * WaCxSRDisabledForSpriteScaling:ivb
+        */
+       if (IS_IVYBRIDGE(dev) && scaled && ilk_disable_lp_wm(dev))
+               intel_wait_for_vblank(dev, intel_plane->pipe);
+
        haswell_update_wm(crtc);
 }
 

diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index 90a3f6d..0bba103 100644 (file)
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -230,7 +230,6 @@ ivb_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
        u32 sprctl, sprscale = 0;
        unsigned long sprsurf_offset, linear_offset;
        int pixel_size = drm_format_plane_cpp(fb->pixel_format, 0);
-       bool scaling_was_enabled = dev_priv->sprite_scaling_enabled;
 
        sprctl = I915_READ(SPRCTL(pipe));
 
@@ -291,21 +290,8 @@ ivb_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
        crtc_w--;
        crtc_h--;
 
-       /*
-        * IVB workaround: must disable low power watermarks for at least
-        * one frame before enabling scaling.  LP watermarks can be re-enabled
-        * when scaling is disabled.
-        */
-       if (crtc_w != src_w || crtc_h != src_h) {
-               dev_priv->sprite_scaling_enabled |= 1 << pipe;
-
-               if (!scaling_was_enabled) {
-                       intel_update_watermarks(crtc);
-                       intel_wait_for_vblank(dev, pipe);
-               }
+       if (crtc_w != src_w || crtc_h != src_h)
                sprscale = SPRITE_SCALE_ENABLE | (src_w << 16) | src_h;
-       } else
-               dev_priv->sprite_scaling_enabled &= ~(1 << pipe);
 
        I915_WRITE(SPRSTRIDE(pipe), fb->pitches[0]);
        I915_WRITE(SPRPOS(pipe), (crtc_y << 16) | crtc_x);
@@ -332,10 +318,6 @@ ivb_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
        I915_MODIFY_DISPBASE(SPRSURF(pipe),
                             i915_gem_obj_ggtt_offset(obj) + sprsurf_offset);
        POSTING_READ(SPRSURF(pipe));
-
-       /* potentially re-enable LP watermarks */
-       if (scaling_was_enabled && !dev_priv->sprite_scaling_enabled)
-               intel_update_watermarks(crtc);
 }
 
 static void
@@ -345,7 +327,6 @@ ivb_disable_plane(struct drm_plane *plane, struct drm_crtc *crtc)
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_plane *intel_plane = to_intel_plane(plane);
        int pipe = intel_plane->pipe;
-       bool scaling_was_enabled = dev_priv->sprite_scaling_enabled;
 
        I915_WRITE(SPRCTL(pipe), I915_READ(SPRCTL(pipe)) & ~SPRITE_ENABLE);
        /* Can't leave the scaler enabled... */
@@ -355,13 +336,7 @@ ivb_disable_plane(struct drm_plane *plane, struct drm_crtc *crtc)
        I915_MODIFY_DISPBASE(SPRSURF(pipe), 0);
        POSTING_READ(SPRSURF(pipe));
 
-       dev_priv->sprite_scaling_enabled &= ~(1 << pipe);
-
        intel_update_sprite_watermarks(plane, crtc, 0, 0, false, false);
-
-       /* potentially re-enable LP watermarks */
-       if (scaling_was_enabled && !dev_priv->sprite_scaling_enabled)
-               intel_update_watermarks(crtc);
 }
 
 static int