[PATCH v6] drm/mediatek: add dma buffer control for drm plane disable

[Yongqiang Niu]

the DMA buffer is released when still accessed by Mediatek display hardware,
this flow can lead to M4U reporting a translation fault warning

add dma buffer control flow in mediatek driver:
get dma buffer when drm plane disable
put dma buffer when overlay really disable

Fixes: 41016fe1028e ("drm: Rename plane->state variables in atomic update and disable")
Signed-off-by: Yongqiang Niu <yongqiang.niu at mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c  | 25 ++++++++++++++++++++++++
 drivers/gpu/drm/mediatek/mtk_drm_drv.c   |  1 +
 drivers/gpu/drm/mediatek/mtk_drm_plane.c | 12 ++++++++++++
 drivers/gpu/drm/mediatek/mtk_drm_plane.h |  1 +
 4 files changed, 39 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index c277b9fae950..188aaa97e5e3 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/dma-buf.h>
 #include <linux/dma-mapping.h>
 #include <linux/mailbox_controller.h>
 #include <linux/of.h>
@@ -283,6 +284,23 @@ struct mtk_ddp_comp *mtk_drm_ddp_comp_for_plane(struct drm_crtc *crtc,
 	return NULL;
 }
 
+static void mtk_drm_dma_buf_put(struct mtk_drm_crtc *mtk_crtc)
+{
+	unsigned int i;
+
+	for (i = 0; i < mtk_crtc->layer_nr; i++) {
+		struct drm_plane *plane = &mtk_crtc->planes[i];
+		struct mtk_plane_state *plane_state;
+
+		plane_state = to_mtk_plane_state(plane->state);
+
+		if (plane_state && plane_state->pending.dma_buf) {
+			dma_buf_put(plane_state->pending.dma_buf);
+			plane_state->pending.dma_buf = NULL;
+		}
+	}
+}
+
 #if IS_REACHABLE(CONFIG_MTK_CMDQ)
 static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
 {
@@ -323,6 +341,8 @@ static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
 		mtk_crtc->pending_async_planes = false;
 	}
 
+	mtk_drm_dma_buf_put(mtk_crtc);
+
 	mtk_crtc->cmdq_vblank_cnt = 0;
 	wake_up(&mtk_crtc->cb_blocking_queue);
 }
@@ -627,9 +647,14 @@ static void mtk_crtc_ddp_irq(void *data)
 	else if (mtk_crtc->cmdq_vblank_cnt > 0 && --mtk_crtc->cmdq_vblank_cnt == 0)
 		DRM_ERROR("mtk_crtc %d CMDQ execute command timeout!\n",
 			  drm_crtc_index(&mtk_crtc->base));
+
+	if (!mtk_crtc->cmdq_client.chan)
+		mtk_drm_dma_buf_put(mtk_crtc);
 #else
 	if (!priv->data->shadow_register)
 		mtk_crtc_ddp_config(crtc, NULL);
+
+	mtk_drm_dma_buf_put(mtk_crtc);
 #endif
 	mtk_drm_finish_page_flip(mtk_crtc);
 }
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
index 2dfaa613276a..4fd232644383 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -1019,4 +1019,5 @@ module_exit(mtk_drm_exit);
 
 MODULE_AUTHOR("YT SHEN <yt.shen at mediatek.com>");
 MODULE_DESCRIPTION("Mediatek SoC DRM driver");
+MODULE_IMPORT_NS(DMA_BUF);
 MODULE_LICENSE("GPL v2");
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_plane.c b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
index ddc9355b06d5..fbfcd0d1a56c 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_plane.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
@@ -12,6 +12,7 @@
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_gem_atomic_helper.h>
 #include <linux/align.h>
+#include <linux/dma-buf.h>
 
 #include "mtk_drm_crtc.h"
 #include "mtk_drm_ddp_comp.h"
@@ -283,6 +284,17 @@ static void mtk_plane_atomic_disable(struct drm_plane *plane,
 	struct drm_plane_state *new_state = drm_atomic_get_new_plane_state(state,
 									   plane);
 	struct mtk_plane_state *mtk_plane_state = to_mtk_plane_state(new_state);
+	struct drm_plane_state *old_state = drm_atomic_get_old_plane_state(state,
+									   plane);
+
+	if (old_state && old_state->fb) {
+		struct drm_gem_object *gem = old_state->fb->obj[0];
+
+		if (gem && gem->dma_buf) {
+			get_dma_buf(gem->dma_buf);
+			mtk_plane_state->pending.dma_buf = gem->dma_buf;
+		}
+	}
 	mtk_plane_state->pending.enable = false;
 	wmb(); /* Make sure the above parameter is set before update */
 	mtk_plane_state->pending.dirty = true;
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_plane.h b/drivers/gpu/drm/mediatek/mtk_drm_plane.h
index 99aff7da0831..3aba0b58ef3c 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_plane.h
+++ b/drivers/gpu/drm/mediatek/mtk_drm_plane.h
@@ -33,6 +33,7 @@ struct mtk_plane_pending_state {
 	bool				async_dirty;
 	bool				async_config;
 	enum drm_color_encoding		color_encoding;
+	struct dma_buf			*dma_buf;
 };
 
 struct mtk_plane_state {
-- 
2.25.1