[RFC 1/3] drm/i915: Added a new 'I915_CPU_MAP_NOT_NEEDED' flag to gem_create ioctl.

[sourab.gupta@intel.com]

From: Sourab Gupta <sourab.gupta@intel.com>

Adding the flag 'I915_CPU_MAP_NOT_NEEDED' to gem_create ioctl.
This is to indicate the driver that direct cpu access to this
buffer object is not needed and hence Driver can opt to use Stolen
area as a backing store for it.

Testcase: igt/gem_stolen_mem

Signed-off-by: Sourab Gupta <sourab.gupta@intel.com>

Signed-off-by: Akash Goel <akash.goel@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h |    6 ++++++
 drivers/gpu/drm/i915/i915_gem.c |   12 +++++++++---
 include/uapi/drm/i915_drm.h     |    3 ++-
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 05cfcc1..8a066a7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1714,6 +1714,12 @@ struct drm_i915_gem_object {
 	unsigned int has_global_gtt_mapping:1;
 	unsigned int has_dma_mapping:1;
 
+	/*
+	 * Is the object not required to be accessed from CPU
+	 */
+	unsigned int cpu_map_not_needed:1;
+
+
 	struct sg_table *pages;
 	int pages_pin_count;
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3618bb0..8421b80 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -224,7 +224,9 @@ static int
 i915_gem_create(struct drm_file *file,
 		struct drm_device *dev,
 		uint64_t size,
-		uint32_t *handle_p)
+		uint32_t *handle_p,
+		uint32_t flags)
+
 {
 	struct drm_i915_gem_object *obj;
 	int ret;
@@ -245,6 +247,10 @@ i915_gem_create(struct drm_file *file,
 	if (ret)
 		return ret;
 
+        if (flags & I915_CPU_MAP_NOT_NEEDED)
+		obj->cpu_map_not_needed = 1;
+
+
 	*handle_p = handle;
 	return 0;
 }
@@ -258,7 +264,7 @@ i915_gem_dumb_create(struct drm_file *file,
 	args->pitch = ALIGN(args->width * DIV_ROUND_UP(args->bpp, 8), 64);
 	args->size = args->pitch * args->height;
 	return i915_gem_create(file, dev,
-			       args->size, &args->handle);
+			       args->size, &args->handle, args->flags);
 }
 
 /**
@@ -271,7 +277,7 @@ i915_gem_create_ioctl(struct drm_device *dev, void *data,
 	struct drm_i915_gem_create *args = data;
 
 	return i915_gem_create(file, dev,
-			       args->size, &args->handle);
+			       args->size, &args->handle, args->flags);
 }
 
 static inline int
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 126bfaa..8625f54 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -431,7 +431,8 @@ struct drm_i915_gem_create {
 	 * Object handles are nonzero.
 	 */
 	__u32 handle;
-	__u32 pad;
+	__u32 flags;
+#define I915_CPU_MAP_NOT_NEEDED 0x1
 };
 
 struct drm_i915_gem_pread {
-- 
1.7.9.5