drm/i915: reorder setup sequence to have irqs for output setup

commit 52d7ecedac3f96fb562cb482c139015372728638 upstream.

Otherwise the new&shiny irq-driven gmbus and dp aux code won't work that
well. Noticed since the dp aux code doesn't have an automatic fallback
with a timeout (since the hw provides for that already).

v2: Simple move drm_irq_install before intel_modeset_gem_init, as
suggested by Ben Widawsky.

v3: Now that interrupts are enabled before all connectors are fully
set up, we might fall over serving a HPD interrupt while things are
still being set up. Instead of jumping through massive hoops and
complicating the code with a separate hpd irq enable step, simply
block out the hotplug work item from doing anything until things are
in place.

v4: Actually, we can enable hotplug processing only after the fbdev is
fully set up, since we call down into the fbdev from the hotplug work
functions. So stick the hpd enabling right next to the poll helper
initialization.

v5: We need to enable irqs before intel_modeset_init, since that
function sets up the outputs.

v6: Fixup cleanup sequence, too.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 19 insertions, 9 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 99daa896105d..5206f24fb087 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1297,19 +1297,21 @@ static int i915_load_modeset_init(struct drm_device *dev)
 	if (ret)
 		goto cleanup_vga_switcheroo;
 
+	ret = drm_irq_install(dev);
+	if (ret)
+		goto cleanup_gem_stolen;
+
+	/* Important: The output setup functions called by modeset_init need
+	 * working irqs for e.g. gmbus and dp aux transfers. */
 	intel_modeset_init(dev);
 
 	ret = i915_gem_init(dev);
 	if (ret)
-		goto cleanup_gem_stolen;
-
-	intel_modeset_gem_init(dev);
+		goto cleanup_irq;
 
 	INIT_WORK(&dev_priv->console_resume_work, intel_console_resume);
 
-	ret = drm_irq_install(dev);
-	if (ret)
-		goto cleanup_gem;
+	intel_modeset_gem_init(dev);
 
 	/* Always safe in the mode setting case. */
 	/* FIXME: do pre/post-mode set stuff in core KMS code */
@@ -1317,7 +1319,10 @@ static int i915_load_modeset_init(struct drm_device *dev)
 
 	ret = intel_fbdev_init(dev);
 	if (ret)
-		goto cleanup_irq;
+		goto cleanup_gem;
+
+	/* Only enable hotplug handling once the fbdev is fully set up. */
+	dev_priv->enable_hotplug_processing = true;
 
 	drm_kms_helper_poll_init(dev);
 
@@ -1326,13 +1331,13 @@ static int i915_load_modeset_init(struct drm_device *dev)
 
 	return 0;
 
-cleanup_irq:
-	drm_irq_uninstall(dev);
 cleanup_gem:
 	mutex_lock(&dev->struct_mutex);
 	i915_gem_cleanup_ringbuffer(dev);
 	mutex_unlock(&dev->struct_mutex);
 	i915_gem_cleanup_aliasing_ppgtt(dev);
+cleanup_irq:
+	drm_irq_uninstall(dev);
 cleanup_gem_stolen:
 	i915_gem_cleanup_stolen(dev);
 cleanup_vga_switcheroo:
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7339a4b89d5f..66ad64f0e26e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -672,6 +672,7 @@ typedef struct drm_i915_private {
 
 	u32 hotplug_supported_mask;
 	struct work_struct hotplug_work;
+	bool enable_hotplug_processing;
 
 	int num_pipe;
 	int num_pch_pll;
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index fe843389c7b4..3c004038550a 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -287,6 +287,10 @@ static void i915_hotplug_work_func(struct work_struct *work)
 	struct drm_mode_config *mode_config = &dev->mode_config;
 	struct intel_encoder *encoder;
 
+	/* HPD irq before everything is fully set up. */
+	if (!dev_priv->enable_hotplug_processing)
+		return;
+
 	mutex_lock(&mode_config->mutex);
 	DRM_DEBUG_KMS("running encoder hotplug functions\n");