drm: rcar-du: Ensure correct suspend/resume ordering with VSP

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.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Link: https://patch.msgid.link/20260323164526.2292491-2-laurent.pinchart+renesas@ideasonboard.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_vsp.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_vsp.c
index 94c22d2db197e78f5ba4385304e5adb47f0314d5..a4a49dcd82330c5a9a690cea7cfe338a12186be8 100644 (file)
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_vsp.c
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_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>
@@ -458,6 +459,9 @@ static void rcar_du_vsp_cleanup(struct drm_device *dev, void *res)
 
        kfree(vsp->planes);
 
+       if (vsp->link)
+               device_link_del(vsp->link);
+
        put_device(vsp->vsp);
 }
 
@@ -482,6 +486,18 @@ int rcar_du_vsp_init(struct rcar_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/rcar-du/rcar_du_vsp.h b/drivers/gpu/drm/renesas/rcar-du/rcar_du_vsp.h
index 67630f0b6599735b20c4eb654e8e91d1fa4ad664..a6731249db34e3639d271d7cdc2a0fce2297fa14 100644 (file)
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_vsp.h
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_vsp.h
@@ -12,6 +12,7 @@
 
 #include <drm/drm_plane.h>
 
+struct device_link;
 struct drm_framebuffer;
 struct rcar_du_format_info;
 struct rcar_du_vsp;
@@ -26,6 +27,7 @@ struct rcar_du_vsp_plane {
 struct rcar_du_vsp {
        unsigned int index;
        struct device *vsp;
+       struct device_link *link;
        struct rcar_du_device *dev;
        struct rcar_du_vsp_plane *planes;
        unsigned int num_planes;