[PATCH v2] drm: rz-du: Ensure correct suspend/resume ordering with VSP

Tommaso Merciai
2026-03-30T14:47:30Z

The VSP serves as an interface to memory and a compositor to the DU. It
therefore needs to be suspended after and resumed before the DU, to be
properly stopped and restarted in a controlled fashion driven by the DU
driver. This currently works by chance. Avoid relying on luck by
enforcing the correct suspend/resume ordering with device links.

Based on similar work done by Laurent Pinchart for R-Car DU.
commit db5be3a7d6bd ("drm: rcar-du: Ensure correct suspend/resume
ordering with VSP")

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
---
v1->v2:
- Collected Laurent Pinchart tag.
- Added commit id of the similar work on R-Car DU.

drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c | 16 ++++++++++++++++
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h | 2 ++
2 files changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c
index bd486377f037..eb626c3cc421 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c
@@ -20,6 +20,7 @@
#include <drm/drm_vblank.h>

#include <linux/bitops.h>
+#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
@@ -293,6 +294,9 @@ static void rzg2l_du_vsp_cleanup(struct drm_device *dev, void *res)
{
struct rzg2l_du_vsp *vsp = res;

+ if (vsp->link)
+ device_link_del(vsp->link);
+
put_device(vsp->vsp);
}

@@ -317,6 +321,18 @@ int rzg2l_du_vsp_init(struct rzg2l_du_vsp *vsp, struct device_node *np,
if (ret < 0)
return ret;

+ /*
+ * Enforce suspend/resume ordering between the DU (consumer) and the
+ * VSP (supplier). The DU will be suspended before and resume after the
+ * VSP.
+ */
+ vsp->link = device_link_add(rcdu->dev, vsp->vsp, DL_FLAG_STATELESS);
+ if (!vsp->link) {
+ dev_err(rcdu->dev, "Failed to create device link to VSP %s\n",
+ dev_name(vsp->vsp));
+ return -EINVAL;
+ }
+
ret = vsp1_du_init(vsp->vsp);
if (ret < 0)
return ret;
diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h
index 322eb80dcbaf..a22aaf0843ed 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h
@@ -15,6 +15,7 @@
#include <linux/scatterlist.h>

struct device;
+struct device_link;
struct drm_framebuffer;
struct rzg2l_du_device;
struct rzg2l_du_format_info;
@@ -29,6 +30,7 @@ struct rzg2l_du_vsp_plane {
struct rzg2l_du_vsp {
unsigned int index;
struct device *vsp;
+ struct device_link *link;
struct rzg2l_du_device *dev;
};

--
2.43.0