drm: Add drm_gem_vram_{pin/unpin}_reserved() and convert mgag200

The new interfaces drm_gem_vram_{pin/unpin}_reserved() are variants of the
GEM VRAM pin/unpin functions that do not reserve the BO during validation.
The mgag200 driver requires this behavior for its cursor handling. The
patch also converts the driver to use the new interfaces.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20190516162746.11636-2-tzimmermann@suse.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

2 files changed, 85 insertions, 8 deletions

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index 8f142b810eb4..a002c03eaf4c 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -255,6 +255,47 @@ int drm_gem_vram_pin(struct drm_gem_vram_object *gbo, unsigned long pl_flag)
 EXPORT_SYMBOL(drm_gem_vram_pin);
 
 /**
+ * drm_gem_vram_pin_reserved() - Pins a GEM VRAM object in a region.
+ * @gbo:	the GEM VRAM object
+ * @pl_flag:	a bitmask of possible memory regions
+ *
+ * Pinning a buffer object ensures that it is not evicted from
+ * a memory region. A pinned buffer object has to be unpinned before
+ * it can be pinned to another region.
+ *
+ * This function pins a GEM VRAM object that has already been
+ * reserved. Use drm_gem_vram_pin() if possible.
+ *
+ * Returns:
+ * 0 on success, or
+ * a negative error code otherwise.
+ */
+int drm_gem_vram_pin_reserved(struct drm_gem_vram_object *gbo,
+			      unsigned long pl_flag)
+{
+	int i, ret;
+	struct ttm_operation_ctx ctx = { false, false };
+
+	if (gbo->pin_count) {
+		++gbo->pin_count;
+		return 0;
+	}
+
+	drm_gem_vram_placement(gbo, pl_flag);
+	for (i = 0; i < gbo->placement.num_placement; ++i)
+		gbo->placements[i].flags |= TTM_PL_FLAG_NO_EVICT;
+
+	ret = ttm_bo_validate(&gbo->bo, &gbo->placement, &ctx);
+	if (ret < 0)
+		return ret;
+
+	gbo->pin_count = 1;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_vram_pin_reserved);
+
+/**
  * drm_gem_vram_unpin() - Unpins a GEM VRAM object
  * @gbo:	the GEM VRAM object
  *
@@ -286,6 +327,40 @@ int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo)
 EXPORT_SYMBOL(drm_gem_vram_unpin);
 
 /**
+ * drm_gem_vram_unpin_reserved() - Unpins a GEM VRAM object
+ * @gbo:	the GEM VRAM object
+ *
+ * This function unpins a GEM VRAM object that has already been
+ * reserved. Use drm_gem_vram_unpin() if possible.
+ *
+ * Returns:
+ * 0 on success, or
+ * a negative error code otherwise.
+ */
+int drm_gem_vram_unpin_reserved(struct drm_gem_vram_object *gbo)
+{
+	int i, ret;
+	struct ttm_operation_ctx ctx = { false, false };
+
+	if (WARN_ON_ONCE(!gbo->pin_count))
+		return 0;
+
+	--gbo->pin_count;
+	if (gbo->pin_count)
+		return 0;
+
+	for (i = 0; i < gbo->placement.num_placement ; ++i)
+		gbo->placements[i].flags &= ~TTM_PL_FLAG_NO_EVICT;
+
+	ret = ttm_bo_validate(&gbo->bo, &gbo->placement, &ctx);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_vram_unpin_reserved);
+
+/**
  * drm_gem_vram_push_to_system() - \
 	Unpins a GEM VRAM object and moves it to system memory
  * @gbo:	the GEM VRAM object
diff --git a/drivers/gpu/drm/mgag200/mgag200_cursor.c b/drivers/gpu/drm/mgag200/mgag200_cursor.c
index 6c1a9d724d85..1c4fc85315a0 100644
--- a/drivers/gpu/drm/mgag200/mgag200_cursor.c
+++ b/drivers/gpu/drm/mgag200/mgag200_cursor.c
@@ -23,9 +23,9 @@ static void mga_hide_cursor(struct mga_device *mdev)
 	WREG8(MGA_CURPOSXL, 0);
 	WREG8(MGA_CURPOSXH, 0);
 	if (mdev->cursor.pixels_1->pin_count)
-		drm_gem_vram_unpin(mdev->cursor.pixels_1);
+		drm_gem_vram_unpin_reserved(mdev->cursor.pixels_1);
 	if (mdev->cursor.pixels_2->pin_count)
-		drm_gem_vram_unpin(mdev->cursor.pixels_2);
+		drm_gem_vram_unpin_reserved(mdev->cursor.pixels_2);
 }
 
 int mga_crtc_cursor_set(struct drm_crtc *crtc,
@@ -96,26 +96,28 @@ int mga_crtc_cursor_set(struct drm_crtc *crtc,
 
 	/* Move cursor buffers into VRAM if they aren't already */
 	if (!pixels_1->pin_count) {
-		ret = drm_gem_vram_pin(pixels_1, DRM_GEM_VRAM_PL_FLAG_VRAM);
+		ret = drm_gem_vram_pin_reserved(pixels_1,
+						DRM_GEM_VRAM_PL_FLAG_VRAM);
 		if (ret)
 			goto out1;
 		gpu_addr = drm_gem_vram_offset(pixels_1);
 		if (gpu_addr < 0) {
-			drm_gem_vram_unpin(pixels_1);
+			drm_gem_vram_unpin_reserved(pixels_1);
 			goto out1;
 		}
 		mdev->cursor.pixels_1_gpu_addr = gpu_addr;
 	}
 	if (!pixels_2->pin_count) {
-		ret = drm_gem_vram_pin(pixels_2, DRM_GEM_VRAM_PL_FLAG_VRAM);
+		ret = drm_gem_vram_pin_reserved(pixels_2,
+						DRM_GEM_VRAM_PL_FLAG_VRAM);
 		if (ret) {
-			drm_gem_vram_unpin(pixels_1);
+			drm_gem_vram_unpin_reserved(pixels_1);
 			goto out1;
 		}
 		gpu_addr = drm_gem_vram_offset(pixels_2);
 		if (gpu_addr < 0) {
-			drm_gem_vram_unpin(pixels_1);
-			drm_gem_vram_unpin(pixels_2);
+			drm_gem_vram_unpin_reserved(pixels_1);
+			drm_gem_vram_unpin_reserved(pixels_2);
 			goto out1;
 		}
 		mdev->cursor.pixels_2_gpu_addr = gpu_addr;