[PATCH 4/5] drm/rcar-du: dsi: Support DSC in the pipeline

[Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>]

Enabling DSI clocks on rcar-du needs some tricks as the DU dot clock is
provided by the DSI. Thus, we call rcar_mipi_dsi_pclk_enable() from the
crtc, when enabling the crtc.

With DSC (added in upcoming patch) in the pipeline, between the DU and
the DSI, the above call path is broken as the crtc tries to call
rcar_mipi_dsi_pclk_enable() on the DSC.

Adjust the rcar_mipi_dsi_pclk_enable() so that it detects the DSC, and
in that case gets the next bridge from the DSC, which is the DSI.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
---
 drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c | 36 +++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c
index 4ef2e3c129ed..085e229bcb0b 100644
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c
@@ -88,6 +88,8 @@ struct dsi_setup_info {
 	const struct dsi_clk_config *clkset;
 };
 
+static const struct drm_bridge_funcs rcar_mipi_dsi_bridge_ops;
+
 static inline struct rcar_mipi_dsi *
 bridge_to_rcar_mipi_dsi(struct drm_bridge *bridge)
 {
@@ -844,15 +846,39 @@ static void rcar_mipi_dsi_atomic_disable(struct drm_bridge *bridge,
 	rcar_mipi_dsi_stop_video(dsi);
 }
 
+/*
+ * We need to skip the DSC bridge when we have DSC in between the DU and
+ * the DSI. We detect the DSI bridge via bridge->funcs, and assume the
+ * next_bridge is the DSI bridge. If this is not the case, the DT data
+ * is wrong (so it shouldn't really happen).
+ */
+static struct drm_bridge *
+rcar_mipi_dsi_resolve_bridge(struct drm_bridge *bridge)
+{
+	if (bridge->funcs != &rcar_mipi_dsi_bridge_ops)
+		bridge = bridge->next_bridge;
+
+	if (!bridge || bridge->funcs != &rcar_mipi_dsi_bridge_ops)
+		return NULL;
+
+	return bridge;
+}
+
 void rcar_mipi_dsi_pclk_enable(struct drm_bridge *bridge,
 			       struct drm_atomic_state *state)
 {
-	struct rcar_mipi_dsi *dsi = bridge_to_rcar_mipi_dsi(bridge);
 	const struct drm_display_mode *mode;
 	struct drm_connector *connector;
+	struct rcar_mipi_dsi *dsi;
 	struct drm_crtc *crtc;
 	int ret;
 
+	bridge = rcar_mipi_dsi_resolve_bridge(bridge);
+	if (WARN_ON(!bridge))
+		return;
+
+	dsi = bridge_to_rcar_mipi_dsi(bridge);
+
 	connector = drm_atomic_get_new_connector_for_encoder(state,
 							     bridge->encoder);
 	crtc = drm_atomic_get_new_connector_state(state, connector)->crtc;
@@ -885,7 +911,13 @@ EXPORT_SYMBOL_GPL(rcar_mipi_dsi_pclk_enable);
 
 void rcar_mipi_dsi_pclk_disable(struct drm_bridge *bridge)
 {
-	struct rcar_mipi_dsi *dsi = bridge_to_rcar_mipi_dsi(bridge);
+	struct rcar_mipi_dsi *dsi;
+
+	bridge = rcar_mipi_dsi_resolve_bridge(bridge);
+	if (WARN_ON(!bridge))
+		return;
+
+	dsi = bridge_to_rcar_mipi_dsi(bridge);
 
 	rcar_mipi_dsi_shutdown(dsi);
 	rcar_mipi_dsi_clk_disable(dsi);

-- 
2.43.0