drm/i915: Sanitize watermarks after hardware state readout (v4)

Although we can do a good job of reading out hardware state, the
graphics firmware may have programmed the watermarks in a creative way
that doesn't match how i915 would have chosen to program them.  We
shouldn't trust the firmware's watermark programming, but should rather
re-calculate how we think WM's should be programmed and then shove those
values into the hardware.

We can do this pretty easily by creating a dummy top-level state,
running it through the check process to calculate all the values, and
then just programming the watermarks for each CRTC.

v2:  Move watermark sanitization after our BIOS fb reconstruction; the
     watermark calculations that we do here need to look at pstate->fb,
     which isn't setup yet in intel_modeset_setup_hw_state(), even
     though we have an enabled & visible plane.

v3:
 - Don't move 'active = optimal' watermark assignment; we just undo
   that change in the next patch anyway.  (Ville)
 - Move atomic helper locking fix to separate patch.  (Maarten)

v4:
 - Grab connection_mutex before calling atomic helper to duplicate
   state.  The connector loop inside the helper will throw a WARN
   if we don't hold something to protect the connector list (and the
   helper itself doesn't try to lock the list).
 - Make failure to calculate watermarks for inherited state a WARN()
   since it probably indicates a serious problem in either our state
   readout code or our watermark code for this platform.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index f9cbd2e81f54c..db3ca41ce16b9 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3617,9 +3617,11 @@ static void skl_update_wm(struct drm_crtc *crtc)
 	dev_priv->wm.skl_hw = *results;
 }
 
-static void ilk_program_watermarks(struct drm_i915_private *dev_priv)
+static void ilk_program_watermarks(struct intel_crtc_state *cstate)
 {
-	struct drm_device *dev = dev_priv->dev;
+	struct drm_crtc *crtc = cstate->base.crtc;
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct intel_pipe_wm lp_wm_1_2 = {}, lp_wm_5_6 = {}, *best_lp_wm;
 	struct ilk_wm_maximums max;
 	struct intel_wm_config *config = &dev_priv->wm.config;
@@ -3650,7 +3652,6 @@ static void ilk_program_watermarks(struct drm_i915_private *dev_priv)
 
 static void ilk_update_wm(struct drm_crtc *crtc)
 {
-	struct drm_i915_private *dev_priv = to_i915(crtc->dev);
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct intel_crtc_state *cstate = to_intel_crtc_state(crtc->state);
 
@@ -3670,7 +3671,7 @@ static void ilk_update_wm(struct drm_crtc *crtc)
 
 	intel_crtc->wm.active.ilk = cstate->wm.optimal.ilk;
 
-	ilk_program_watermarks(dev_priv);
+	ilk_program_watermarks(cstate);
 }
 
 static void skl_pipe_wm_active_state(uint32_t val,
@@ -7000,6 +7001,7 @@ void intel_init_pm(struct drm_device *dev)
 		     dev_priv->wm.spr_latency[0] && dev_priv->wm.cur_latency[0])) {
 			dev_priv->display.update_wm = ilk_update_wm;
 			dev_priv->display.compute_pipe_wm = ilk_compute_pipe_wm;
+			dev_priv->display.program_watermarks = ilk_program_watermarks;
 		} else {
 			DRM_DEBUG_KMS("Failed to read display plane latency. "
 				      "Disable CxSR\n");