[Intel-gfx] [PATCH 3/4] drm/i915: Allow the module to load even if we fail to setup rings

[Chris Wilson]

Even without enabling the ringbuffers to allow command execution, we can
still control the display engines to enable modesetting. So make the
ringbuffer initialization failure soft, and mark the GPU as wedged
instead.

v2: Only treat an EIO from ring initialisation as a soft failure, and
abort module load for any other failure, such as allocation failures.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 5be21372d0c1..12548589a234 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4663,15 +4663,11 @@ i915_gem_init_hw(struct drm_device *dev)
 	 * the do_switch), but before enabling PPGTT. So don't move this.
 	 */
 	ret = i915_gem_context_enable(dev_priv);
-	if (ret) {
+	if (ret && ret != -EIO) {
 		DRM_ERROR("Context enable failed %d\n", ret);
-		goto err_out;
+		i915_gem_cleanup_ringbuffer(dev);
 	}
 
-	return 0;
-
-err_out:
-	i915_gem_cleanup_ringbuffer(dev);
 	return ret;
 }
 
@@ -4699,18 +4695,20 @@ int i915_gem_init(struct drm_device *dev)
 	}
 
 	ret = i915_gem_init_hw(dev);
-	mutex_unlock(&dev->struct_mutex);
-	if (ret) {
-		WARN_ON(dev_priv->mm.aliasing_ppgtt);
-		i915_gem_context_fini(dev);
-		drm_mm_takedown(&dev_priv->gtt.base.mm);
-		return ret;
+	if (ret == -EIO) {
+		/* Allow ring initialisation to fail by marking the GPU as
+		 * wedged. But we only want to do this where the GPU is angry,
+		 * for all other failure, such as an allocation failure, bail.
+		 */
+		atomic_set_mask(I915_WEDGED, &dev_priv->gpu_error.reset_counter);
+		ret = 0;
 	}
+	mutex_unlock(&dev->struct_mutex);
 
 	/* Allow hardware batchbuffers unless told otherwise, but not for KMS. */
 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		dev_priv->dri1.allow_batchbuffer = 1;
-	return 0;
+	return ret;
 }
 
 void
-- 
1.9.1