[PATCH 0/8] drm/sun4i: Make both display pipeline work together

Hi everyone,

Previously I added support for two display pipelines for the sun4i-drm
driver. At the time we did not have support for downstream encoders to
actually test the second pipeline, nor having both pipelines active at
the same time.

With HDMI encoder support now merged and support for it on sun6i in
progress, we are now able to test both pipelines being active at the
same time, with LCD output from one and HDMI from the other. Testing
has revealed some more issues, such as component probing order. Also,
we found out that muxing between the display backend and TCON was
possible, and required for the second pipeline to work as intended.
Last, the number of CRTCs provided to drm_vblank_init needs to be
increased for vblanks to work properly.

This patch series does a few things:

  - Fix endpoint IDs so they conform to what the DT binding stipulates.

  - Change the order the individual components are queued up.

  - Fix how the TCON gets its ID when the backend-TCON mux is present.

  - Support the input mux in the TCON (which selects which backend to
    use on the A31/A31s).

  - Fix the drm_vblank_init call and pass the correct number of crtcs.

  - Add the cross pipeline connections between the DRCs and TCONs on
    the A31, conforming to the DT binding and what the hardware is
    capable of.

More details are available in each individual commit. Please have a look.

Regards
ChenYu


Chen-Yu Tsai (8):
  ARM: dts: sun6i: Fix endpoint IDs in second display pipeline
  drm/sun4i: add components in breadth first traversal order
  drm/sun4i: tcon: Check for multiple paths between TCONs and backends
  drm/sun4i: tcon: get TCON ID and matching engine with remote endpoint
    ID
  drm/sun4i: tcon: Simplify sun4i_tcon_find_engine_traverse for one
    input
  drm/sun4i: tcon: Support backend input mux
  drm/sun4i: call drm_vblank_init with correct number of crtcs
  ARM: dts: sun6i: Add cross pipeline connections between DRCs and TCONs

 arch/arm/boot/dts/sun6i-a31.dtsi   |  32 +++++--
 drivers/gpu/drm/sun4i/sun4i_drv.c  |  91 +++++++++++++++---
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 191 +++++++++++++++++++++++++++++++++----
 drivers/gpu/drm/sun4i/sun4i_tcon.h |   3 +
 4 files changed, 276 insertions(+), 41 deletions(-)

-- 
2.14.1

The patch b317fa3ba11a ("drm/sun4i: tcon: Find matching display backend
by device node matching") assumed a one-to-one mapping between TCONs
and backends. This turned out wrong, as we found muxing controls in the
TCON of the A31, and undocumented usage of the backend output selector
of the A20.

Make sun4i_tcon_find_engine() bail out if the current node has multiple
input connections.

Fixes: b317fa3ba11a ("drm/sun4i: tcon: Find matching display backend
		      by device node matching")
Signed-off-by: Chen-Yu Tsai <redacted>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index eb32676d5b01..065654dbfb2c 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -473,6 +473,20 @@ static struct sunxi_engine *sun4i_tcon_find_engine(struct sun4i_drv *drv,
 	if (!port)
 		return ERR_PTR(-EINVAL);
 
+	/*
+	 * This only works if there is only one path from the TCON
+	 * to any display engine. Otherwise the probe order of the
+	 * TCONs and display engines is not guaranteed. They may
+	 * either bind to the wrong one, or worse, bind to the same
+	 * one if additional checks are not done.
+	 *
+	 * Bail out if there are multiple input connections.
+	 */
+	if (of_get_available_child_count(port) != 1) {
+		of_node_put(port);
+		return ERR_PTR(-EINVAL);
+	}
+
 	for_each_available_child_of_node(port, ep) {
 		remote = of_graph_get_remote_port_parent(ep);
 		if (!remote)

-- 
2.14.1

Now that sun4i_tcon_find_engine_traverse() usage is restricted to the
single input case, we can remove the for_each_available_child_of_node
loop.

While at it, consolidate all the of_node_put calls into a common exit
path.

Signed-off-by: Chen-Yu Tsai <redacted>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 51 +++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 33c20d2f9fb1..e9ab03f0bf6e 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -468,7 +468,7 @@ sun4i_tcon_find_engine_traverse(struct sun4i_drv *drv,
 				struct device_node *node)
 {
 	struct device_node *port, *ep, *remote;
-	struct sunxi_engine *engine;
+	struct sunxi_engine *engine = ERR_PTR(-EINVAL);
 
 	port = of_graph_get_port_by_id(node, 0);
 	if (!port)

@@ -483,35 +483,34 @@ sun4i_tcon_find_engine_traverse(struct sun4i_drv *drv,
 	 *
 	 * Bail out if there are multiple input connections.
 	 */
-	if (of_get_available_child_count(port) != 1) {
-		of_node_put(port);
-		return ERR_PTR(-EINVAL);
-	}
+	if (of_get_available_child_count(port) != 1)
+		goto out_put_port;
 
-	for_each_available_child_of_node(port, ep) {
-		remote = of_graph_get_remote_port_parent(ep);
-		if (!remote)
-			continue;
+	/* Get the first connection without specifying an ID */
+	ep = of_get_next_available_child(port, NULL);
+	if (!ep)
+		goto out_put_port;
 
-		/* does this node match any registered engines? */
-		list_for_each_entry(engine, &drv->engine_list, list) {
-			if (remote == engine->node) {
-				of_node_put(remote);
-				of_node_put(port);
-				return engine;
-			}
-		}
+	remote = of_graph_get_remote_port_parent(ep);
+	if (!remote)
+		goto out_put_ep;
 
-		/* keep looking through upstream ports */
-		engine = sun4i_tcon_find_engine_traverse(drv, remote);
-		if (!IS_ERR(engine)) {
-			of_node_put(remote);
-			of_node_put(port);
-			return engine;
-		}
-	}
+	/* does this node match any registered engines? */
+	list_for_each_entry(engine, &drv->engine_list, list)
+		if (remote == engine->node)
+			goto out_put_remote;
 
-	return ERR_PTR(-EINVAL);
+	/* keep looking through upstream ports */
+	engine = sun4i_tcon_find_engine_traverse(drv, remote);
+
+out_put_remote:
+	of_node_put(remote);
+out_put_ep:
+	of_node_put(ep);
+out_put_port:
+	of_node_put(port);
+
+	return engine;
 }
 
 /*

-- 
2.14.1