[PATCH v4 2/3] drm: Add and export function drm_gem_cma_sync_data

[Paul Cercueil]

This function can be used by drivers that use damage clips and have
CMA GEM objects backed by non-coherent memory. Calling this function
in a plane's .atomic_update ensures that all the data in the backing
memory have been written to RAM.

v3: - Only sync data if using GEM objects backed by non-coherent memory.
    - Use a drm_device pointer instead of device pointer in prototype

Signed-off-by: Paul Cercueil <paul at crapouillou.net>
---
 drivers/gpu/drm/drm_gem_cma_helper.c | 55 ++++++++++++++++++++++++++++
 include/drm/drm_gem_cma_helper.h     |  5 +++
 2 files changed, 60 insertions(+)

diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 235c7a63da2b..41f309e0e049 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -17,9 +17,14 @@
 #include <linux/slab.h>
 
 #include <drm/drm.h>
+#include <drm/drm_damage_helper.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_framebuffer.h>
 #include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_plane.h>
 #include <drm/drm_vma_manager.h>
 
 /**
@@ -576,3 +581,53 @@ drm_gem_cma_prime_import_sg_table_vmap(struct drm_device *dev,
 	return obj;
 }
 EXPORT_SYMBOL(drm_gem_cma_prime_import_sg_table_vmap);
+
+/**
+ * drm_gem_cma_sync_data - Sync GEM object to non-coherent backing memory
+ * @drm: DRM device
+ * @old_state: Old plane state
+ * @state: New plane state
+ *
+ * This function can be used by drivers that use damage clips and have
+ * CMA GEM objects backed by non-coherent memory. Calling this function
+ * in a plane's .atomic_update ensures that all the data in the backing
+ * memory have been written to RAM.
+ */
+void drm_gem_cma_sync_data(struct drm_device *drm,
+			   struct drm_plane_state *old_state,
+			   struct drm_plane_state *state)
+{
+	const struct drm_format_info *finfo = state->fb->format;
+	struct drm_atomic_helper_damage_iter iter;
+	const struct drm_gem_cma_object *cma_obj;
+	unsigned int offset, i;
+	struct drm_rect clip;
+	dma_addr_t daddr;
+
+	for (i = 0; i < finfo->num_planes; i++) {
+		cma_obj = drm_fb_cma_get_gem_obj(state->fb, i);
+
+		if (cma_obj->map_noncoherent)
+			break;
+	}
+
+	/* No non-coherent buffers - no need to sync anything. */
+	if (i == finfo->num_planes)
+		return;
+
+	drm_atomic_helper_damage_iter_init(&iter, old_state, state);
+
+	drm_atomic_for_each_plane_damage(&iter, &clip) {
+		for (i = 0; i < finfo->num_planes; i++) {
+			daddr = drm_fb_cma_get_gem_addr(state->fb, state, i);
+
+			/* Ignore x1/x2 values, invalidate complete lines */
+			offset = clip.y1 * state->fb->pitches[i];
+
+			dma_sync_single_for_device(drm->dev, daddr + offset,
+				       (clip.y2 - clip.y1) * state->fb->pitches[i],
+				       DMA_TO_DEVICE);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(drm_gem_cma_sync_data);
diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
index cd13508acbc1..76af066ae3a7 100644
--- a/include/drm/drm_gem_cma_helper.h
+++ b/include/drm/drm_gem_cma_helper.h
@@ -7,6 +7,7 @@
 #include <drm/drm_gem.h>
 
 struct drm_mode_create_dumb;
+struct drm_plane_state;
 
 /**
  * struct drm_gem_cma_object - GEM object backed by CMA memory allocations
@@ -185,4 +186,8 @@ drm_gem_cma_prime_import_sg_table_vmap(struct drm_device *drm,
 				       struct dma_buf_attachment *attach,
 				       struct sg_table *sgt);
 
+void drm_gem_cma_sync_data(struct drm_device *drm,
+			   struct drm_plane_state *old_state,
+			   struct drm_plane_state *state);
+
 #endif /* __DRM_GEM_CMA_HELPER_H__ */
-- 
2.30.2