drm/i915/gen9: Initialize intel_state->active_crtcs during WM sanitization (v2)

intel_state->active_crtcs is usually only initialized when doing a
modeset.  During our first atomic commit after boot, we're effectively
faking a modeset to sanitize the DDB/wm setup, so ensure that this field
gets initialized before use.

v2:
 - Don't clobber active_crtcs if our first commit really is a modeset
   (Maarten)
 - Grab connection_mutex when faking a modeset during sanitization
   (Maarten)

Reported-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Tested-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466196140-16336-2-git-send-email-matthew.d.roper@intel.com
Cc: stable@vger.kernel.org #v4.7+
(cherry picked from commit 1b54a880b250acc226b13cea221b90aa1b3e37dd)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index d5deb58a2128..e9763a89f3d7 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3912,9 +3912,24 @@ skl_compute_ddb(struct drm_atomic_state *state)
          * pretend that all pipes switched active status so that we'll
          * ensure a full DDB recompute.
          */
-        if (dev_priv->wm.distrust_bios_wm)
+        if (dev_priv->wm.distrust_bios_wm) {
+                ret = drm_modeset_lock(&dev->mode_config.connection_mutex,
+                                       state->acquire_ctx);
+                if (ret)
+                        return ret;
+
                 intel_state->active_pipe_changes = ~0;
 
+                /*
+                 * We usually only initialize intel_state->active_crtcs if we
+                 * we're doing a modeset; make sure this field is always
+                 * initialized during the sanitization process that happens
+                 * on the first commit too.
+                 */
+                if (!intel_state->modeset)
+                        intel_state->active_crtcs = dev_priv->active_crtcs;
+        }
+
         /*
          * If the modeset changes which CRTC's are active, we need to
          * recompute the DDB allocation for *all* active pipes, even