[Intel-gfx] [PATCH v6 01/14] drm/i915: Defer default hardware context initialisation until first open

[yu.dai at intel.com]

From: Dave Gordon <david.s.gordon at intel.com>

In order to fully initialise the default contexts, we have to execute
batchbuffer commands on the GPU engines. But we can't do that until any
required firmware has been loaded, which may not be possible during
driver load, because the filesystem(s) containing the firmware may not
be mounted until later.

Therefore, we now allow the first call to the firmware-loading code to
return -EAGAIN to indicate that it's not yet ready, and that it should
be retried when the device is first opened from user code, by which
time we expect that all required filesystems will have been mounted.
The late-retry code will then re-attempt to load the firmware if the
early attempt failed.

Issue: VIZ-4884
Signed-off-by: Dave Gordon <david.s.gordon at intel.com>
Signed-off-by: Alex Dai <yu.dai at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h         |  1 +
 drivers/gpu/drm/i915/i915_gem.c         |  4 +++-
 drivers/gpu/drm/i915/i915_gem_context.c | 31 ++++++++++++++++++++++++++-----
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index f3c77ca..31e13e9 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1757,6 +1757,7 @@ struct drm_i915_private {
 	/* hda/i915 audio component */
 	bool audio_component_registered;
 
+	bool contexts_ready;
 	uint32_t hw_context_size;
 	struct list_head context_list;
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e8f6f4c..db59821 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4865,7 +4865,9 @@ i915_gem_init_hw(struct drm_device *dev)
 	}
 
 	ret = i915_gem_context_enable(dev_priv);
-	if (ret && ret != -EIO) {
+	if (ret == 0) {
+		dev_priv->contexts_ready = true;
+	} else if (ret && ret != -EIO) {
 		DRM_ERROR("Context enable failed %d\n", ret);
 		i915_gem_cleanup_ringbuffer(dev);
 
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 5a47eb5..0edae87 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -447,23 +447,44 @@ static int context_idr_cleanup(int id, void *p, void *data)
 	return 0;
 }
 
+/* Complete any late initialisation here */
+static int i915_gem_context_first_open(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int ret;
+
+	ret = i915_gem_context_enable(dev_priv);
+	if (ret == 0)
+		dev_priv->contexts_ready = true;
+	return ret;
+}
+
 int i915_gem_context_open(struct drm_device *dev, struct drm_file *file)
 {
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_file_private *file_priv = file->driver_priv;
 	struct intel_context *ctx;
+	int ret = 0;
 
 	idr_init(&file_priv->context_idr);
 
 	mutex_lock(&dev->struct_mutex);
-	ctx = i915_gem_create_context(dev, file_priv);
+
+	if (!dev_priv->contexts_ready)
+		ret = i915_gem_context_first_open(dev);
+
+	if (ret == 0) {
+		ctx = i915_gem_create_context(dev, file_priv);
+		if (IS_ERR(ctx))
+			ret = PTR_ERR(ctx);
+	}
+
 	mutex_unlock(&dev->struct_mutex);
 
-	if (IS_ERR(ctx)) {
+	if (ret)
 		idr_destroy(&file_priv->context_idr);
-		return PTR_ERR(ctx);
-	}
 
-	return 0;
+	return ret;
 }
 
 void i915_gem_context_close(struct drm_device *dev, struct drm_file *file)
-- 
1.9.1