[Intel-gfx] [PATCH 5/5 v2] drm/i915: Fix atomic state when reusing the firmware fb

[Damien Lespiau]

Right now, we get a warning when taking over the firmware fb:

  [drm:drm_atomic_plane_check] FB set but no CRTC

with the following backtrace:

  [<ffffffffa010339d>] drm_atomic_check_only+0x35d/0x510 [drm]
  [<ffffffffa0103567>] drm_atomic_commit+0x17/0x60 [drm]
  [<ffffffffa00a6ccd>] drm_atomic_helper_plane_set_property+0x8d/0xd0 [drm_kms_helper]
  [<ffffffffa00f1fed>] drm_mode_plane_set_obj_prop+0x2d/0x90 [drm]
  [<ffffffffa00a8a1b>] restore_fbdev_mode+0x6b/0xf0 [drm_kms_helper]
  [<ffffffffa00aa969>] drm_fb_helper_restore_fbdev_mode_unlocked+0x29/0x80 [drm_kms_helper]
  [<ffffffffa00aa9e2>] drm_fb_helper_set_par+0x22/0x50 [drm_kms_helper]
  [<ffffffffa050a71a>] intel_fbdev_set_par+0x1a/0x60 [i915]
  [<ffffffff813ad444>] fbcon_init+0x4f4/0x580

That's because we update the plane state with the fb from the firmware, but we
never associate the plane to that CRTC.

We don't quite have the full DRM take over from HW state just yet, so
fake enough of the plane atomic state to pass the checks.

v2: Fix the state on which we set the CRTC in the case we're sharing the
    initial fb with another pipe. (Matt)

Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 86cbc77..074f204 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2439,8 +2439,12 @@ intel_find_plane_obj(struct intel_crtc *intel_crtc,
 		return;
 
 	if (intel_alloc_plane_obj(intel_crtc, plane_config)) {
-		intel_crtc->base.primary->fb = &plane_config->fb->base;
-		update_state_fb(intel_crtc->base.primary);
+		struct drm_plane *primary = intel_crtc->base.primary;
+
+		primary->fb = &plane_config->fb->base;
+		primary->state->crtc = &intel_crtc->base;
+		update_state_fb(primary);
+
 		return;
 	}
 
@@ -2464,11 +2468,14 @@ intel_find_plane_obj(struct intel_crtc *intel_crtc,
 			continue;
 
 		if (i915_gem_obj_ggtt_offset(obj) == plane_config->base) {
+			struct drm_plane *primary = intel_crtc->base.primary;
+
 			if (obj->tiling_mode != I915_TILING_NONE)
 				dev_priv->preserve_bios_swizzle = true;
 
 			drm_framebuffer_reference(c->primary->fb);
-			intel_crtc->base.primary->fb = c->primary->fb;
+			primary->fb = c->primary->fb;
+			primary->state->crtc = &intel_crtc->base;
 			update_state_fb(intel_crtc->base.primary);
 			obj->frontbuffer_bits |= INTEL_FRONTBUFFER_PRIMARY(intel_crtc->pipe);
 			break;
-- 
1.8.3.1