[Intel-gfx] [CI 1/2] drm/i915/gem: Allow backends to override pread implementation

[Chris Wilson]

From: Matthew Auld <matthew.auld at intel.com>

As there are more and more complicated interactions between the different
backing stores and userspace, push the control into the backends rather
than accumulate them all inside the ioctl handlers.

Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gem/i915_gem_object_types.h | 2 ++
 drivers/gpu/drm/i915/i915_gem.c                  | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
index fedfebf13344..e2d9b7e1e152 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
@@ -56,6 +56,8 @@ struct drm_i915_gem_object_ops {
 	void (*truncate)(struct drm_i915_gem_object *obj);
 	void (*writeback)(struct drm_i915_gem_object *obj);
 
+	int (*pread)(struct drm_i915_gem_object *obj,
+		     const struct drm_i915_gem_pread *arg);
 	int (*pwrite)(struct drm_i915_gem_object *obj,
 		      const struct drm_i915_gem_pwrite *arg);
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index bb0c12975f38..d58fe1ddc3e1 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -527,6 +527,12 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data,
 
 	trace_i915_gem_object_pread(obj, args->offset, args->size);
 
+	ret = -ENODEV;
+	if (obj->ops->pread)
+		ret = obj->ops->pread(obj, args);
+	if (ret != -ENODEV)
+		goto out;
+
 	ret = i915_gem_object_wait(obj,
 				   I915_WAIT_INTERRUPTIBLE,
 				   MAX_SCHEDULE_TIMEOUT);
-- 
2.20.1