drm/i915: add fbc enable flag, but disable by default

FBC has too many corner cases that we don't currently deal with, so
disable it by default so we can enable more important features like RC6,
which conflicts in some configurations.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=31742
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Keith Packard <keithp@keithp.com>

4 files changed, 14 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 183eaac8980a..51c2257b11e6 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1065,6 +1065,9 @@ static int i915_fbc_status(struct seq_file *m, void *unused)
                 case FBC_MULTIPLE_PIPES:
                         seq_printf(m, "multiple pipes are enabled");
                         break;
+                case FBC_MODULE_PARAM:
+                        seq_printf(m, "disabled per module param (default off)");
+                        break;
                 default:
                         seq_printf(m, "unknown reason");
                 }
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 8c4fcbb8a4cb..4c9e92f8abc2 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -55,6 +55,9 @@ module_param_named(semaphores, i915_semaphores, int, 0600);
 unsigned int i915_enable_rc6 = 0;
 module_param_named(i915_enable_rc6, i915_enable_rc6, int, 0600);
 
+unsigned int i915_enable_fbc = 0;
+module_param_named(i915_enable_fbc, i915_enable_fbc, int, 0600);
+
 unsigned int i915_lvds_downclock = 0;
 module_param_named(lvds_downclock, i915_lvds_downclock, int, 0400);
 
@@ -169,7 +172,7 @@ static const struct intel_device_info intel_ironlake_d_info = {
 static const struct intel_device_info intel_ironlake_m_info = {
         .gen = 5, .is_mobile = 1,
         .need_gfx_hws = 1, .has_hotplug = 1,
-        .has_fbc = 0, /* disabled due to buggy hardware */
+        .has_fbc = 1,
         .has_bsd_ring = 1,
 };
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 3a1c27718065..ee660355ae68 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -250,6 +250,7 @@ enum no_fbc_reason {
         FBC_BAD_PLANE, /* fbc not supported on plane */
         FBC_NOT_TILED, /* buffer not tiled */
         FBC_MULTIPLE_PIPES, /* more than one pipe active */
+        FBC_MODULE_PARAM,
 };
 
 enum intel_pch {
@@ -995,6 +996,7 @@ extern unsigned int i915_lvds_downclock;
 extern unsigned int i915_panel_use_ssc;
 extern int i915_vbt_sdvo_panel_type;
 extern unsigned int i915_enable_rc6;
+extern unsigned int i915_enable_fbc;
 
 extern int i915_suspend(struct drm_device *dev, pm_message_t state);
 extern int i915_resume(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 5ec74df2627e..81ad654f3544 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1731,6 +1731,11 @@ static void intel_update_fbc(struct drm_device *dev)
         intel_fb = to_intel_framebuffer(fb);
         obj = intel_fb->obj;
 
+        if (!i915_enable_fbc) {
+                DRM_DEBUG_KMS("fbc disabled per module param (default off)\n");
+                dev_priv->no_fbc_reason = FBC_MODULE_PARAM;
+                goto out_disable;
+        }
         if (intel_fb->obj->base.size > dev_priv->cfb_size) {
                 DRM_DEBUG_KMS("framebuffer too large, disabling "
                               "compression\n");