[Intel-gfx] [PATCH 1/7] drm/i915: Disable primary plane if we fail to reconstruct BIOS fb (v2)

[Matt Roper]

If we fail to reconstruct the BIOS fb (e.g., because the FB is too
large), we'll be left with plane state that indicates the primary plane
is visible yet has a NULL fb.  This mismatch causes problems later on
(e.g., for the watermark code).  Since we've failed to reconstruct the
BIOS FB, the best solution is to just disable the primary plane and
pretend the BIOS never had it enabled.

v2: Add intel_pre_disable_primary() call (Maarten)

Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala at intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
As previously noted, this might also fix some GPU hangs on older platforms
(unconfirmed).  Potential bugzillas include:

        https://bugs.freedesktop.org/show_bug.cgi?id=89319
        https://bugs.freedesktop.org/show_bug.cgi?id=87677
        https://bugs.freedesktop.org/show_bug.cgi?id=89146
        https://bugs.freedesktop.org/show_bug.cgi?id=91653

This should probably go into -fixes (and possibly stable if we get confirmation
on any of those bugzillas?)

 drivers/gpu/drm/i915/intel_display.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4959adb..e5c0807 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -116,6 +116,7 @@ static void skylake_pfit_enable(struct intel_crtc *crtc);
 static void ironlake_pfit_disable(struct intel_crtc *crtc, bool force);
 static void ironlake_pfit_enable(struct intel_crtc *crtc);
 static void intel_modeset_setup_hw_state(struct drm_device *dev);
+static void intel_pre_disable_primary(struct drm_crtc *crtc);
 
 typedef struct {
 	int	min, max;
@@ -2597,6 +2598,8 @@ intel_find_initial_plane_obj(struct intel_crtc *intel_crtc,
 	struct drm_i915_gem_object *obj;
 	struct drm_plane *primary = intel_crtc->base.primary;
 	struct drm_plane_state *plane_state = primary->state;
+	struct drm_crtc_state *crtc_state = intel_crtc->base.state;
+	struct intel_plane *intel_plane = to_intel_plane(primary);
 	struct drm_framebuffer *fb;
 
 	if (!plane_config->fb)
@@ -2633,6 +2636,18 @@ intel_find_initial_plane_obj(struct intel_crtc *intel_crtc,
 		}
 	}
 
+	/*
+	 * We've failed to reconstruct the BIOS FB.  Current display state
+	 * indicates that the primary plane is visible, but has a NULL FB,
+	 * which will lead to problems later if we don't fix it up.  The
+	 * simplest solution is to just disable the primary plane now and
+	 * pretend the BIOS never had it enabled.
+	 */
+	to_intel_plane_state(plane_state)->visible = false;
+	crtc_state->plane_mask &= ~(1 << drm_plane_index(primary));
+	intel_pre_disable_primary(&intel_crtc->base);
+	intel_plane->disable_plane(primary, &intel_crtc->base);
+
 	return;
 
 valid_fb:
-- 
2.1.4