[PATCH] drm/bridge: lt9211: drop delayed work

[Philipp Zabel <p.zabel@pengutronix.de>]

Replace the asynchronous work item with synchronous initialization in
lt9211_atomic_enable. This should fix 3 issues flagged by sashiko [1].

The next bridge or panel in the chain may depend on the LVDS signal
being active after atomic_enable, so arbitrarily deferring bridge
initialization is not an option.

If deferring initialization into an asynchronous work item fixes DSI
stream detection, there might be a bug in the upstream display
controller or MIPI DSI host controller bridge drivers, as the DSI
signal should already be streaming when lt9211_atomic_enable is called.

[1] https://lore.kernel.org/all/20260924160816.ED8F31F0089E@smtp.kernel.org/

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/gpu/drm/bridge/lontium-lt9211.c | 121 ++++++++----------------
 1 file changed, 38 insertions(+), 83 deletions(-)

diff --git a/drivers/gpu/drm/bridge/lontium-lt9211.c b/drivers/gpu/drm/bridge/lontium-lt9211.c
index 9226d967b271..244979fb9ae6 100644
--- a/drivers/gpu/drm/bridge/lontium-lt9211.c
+++ b/drivers/gpu/drm/bridge/lontium-lt9211.c
@@ -20,7 +20,6 @@
 #include <linux/of_graph.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
-#include <linux/workqueue.h>
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
@@ -72,14 +71,6 @@ struct lt9211 {
 	bool				lvds_dual_link;
 	bool				lvds_dual_link_even_odd_swap;
 	const struct lt9211_chip_data	*chip_data;
-	/* LT9211C specific fields */
-	struct workqueue_struct		*wq;
-	struct work_struct		lt9211_work;
-	struct drm_crtc			*lt9211c_crtc;
-	struct drm_display_mode	lt9211c_mode;
-	bool				lt9211c_bpp24;
-	bool				lt9211c_jeida;
-	bool				lt9211c_de_high;
 };
 
 static const struct regmap_range lt9211_rw_ranges[] = {
@@ -1157,51 +1148,6 @@ static int lt9211c_configure_tx(struct lt9211 *ctx, bool jeida, bool bpp24,
 	return 0;
 }
 
-static void lt9211_work_func(struct work_struct *work)
-{
-	struct lt9211 *ctx = container_of(work, struct lt9211, lt9211_work);
-	const struct drm_display_mode *mode = &ctx->lt9211c_mode;
-	int ret;
-
-	/* wait for vblank irq to correctly configure bridge and autodetect stream */
-	ret = drm_crtc_wait_one_vblank(ctx->lt9211c_crtc);
-	if (ret) {
-		dev_err(ctx->dev, "LT9211C: wait for vblank failed: %d\n", ret);
-		return;
-	}
-
-	ret = lt9211c_configure_rx(ctx);
-	if (ret) {
-		dev_err(ctx->dev, "LT9211C: configure_rx failed: %d\n", ret);
-		return;
-	}
-
-	ret = lt9211c_autodetect_rx(ctx, mode);
-	if (ret) {
-		dev_err(ctx->dev, "LT9211C: autodetect_rx failed: %d\n", ret);
-		return;
-	}
-
-	ret = lt9211c_configure_timing(ctx, mode);
-	if (ret) {
-		dev_err(ctx->dev, "LT9211C: configure_timing failed: %d\n", ret);
-		return;
-	}
-
-	ret = lt9211c_configure_plls(ctx, mode);
-	if (ret) {
-		dev_err(ctx->dev, "LT9211C: configure_plls failed: %d\n", ret);
-		return;
-	}
-
-	ret = lt9211c_configure_tx(ctx, ctx->lt9211c_jeida, ctx->lt9211c_bpp24,
-				   ctx->lt9211c_de_high, mode);
-	if (ret) {
-		dev_err(ctx->dev, "LT9211C: configure_tx failed: %d\n", ret);
-		return;
-	}
-}
-
 static void lt9211_atomic_enable(struct drm_bridge *bridge,
 				 struct drm_atomic_state *state)
 {
@@ -1272,17 +1218,45 @@ static void lt9211_atomic_enable(struct drm_bridge *bridge,
 		return;
 
 	if (ctx->chip_data->chip_type == LT9211C) {
-		drm_mode_copy(&ctx->lt9211c_mode, mode);
-		ctx->lt9211c_bpp24 = lvds_format_24bpp;
-		ctx->lt9211c_jeida = lvds_format_jeida;
-		ctx->lt9211c_de_high = !!(bus_flags & DRM_BUS_FLAG_DE_HIGH);
-		ctx->lt9211c_crtc = crtc;
+		/* wait for vblank irq to correctly configure bridge and autodetect stream */
+		ret = drm_crtc_wait_one_vblank(crtc);
+		if (ret) {
+			dev_err(ctx->dev, "LT9211C: wait for vblank failed: %d\n", ret);
+			return;
+		}
 
-		/*
-		 * Needs a live DSI stream to auto-detect RX resolution/format;
-		 * defer bridge configuration until vblank inside the work item.
-		 */
-		queue_work(ctx->wq, &ctx->lt9211_work);
+		ret = lt9211c_configure_rx(ctx);
+		if (ret) {
+			dev_err(ctx->dev, "LT9211C: configure_rx failed: %d\n", ret);
+			return;
+		}
+
+		ret = lt9211c_autodetect_rx(ctx, mode);
+		if (ret) {
+			dev_err(ctx->dev, "LT9211C: autodetect_rx failed: %d\n", ret);
+			return;
+		}
+
+		ret = lt9211c_configure_timing(ctx, mode);
+		if (ret) {
+			dev_err(ctx->dev, "LT9211C: configure_timing failed: %d\n", ret);
+			return;
+		}
+
+		ret = lt9211c_configure_plls(ctx, mode);
+		if (ret) {
+			dev_err(ctx->dev, "LT9211C: configure_plls failed: %d\n", ret);
+			return;
+		}
+
+		ret = lt9211c_configure_tx(ctx, lvds_format_jeida, lvds_format_24bpp,
+					   bus_flags & DRM_BUS_FLAG_DE_HIGH, mode);
+		if (ret) {
+			dev_err(ctx->dev, "LT9211C: configure_tx failed: %d\n", ret);
+			return;
+		}
+
+		dev_dbg(ctx->dev, "LT9211C enabled.\n");
 		return;
 	}
 
@@ -1320,9 +1294,6 @@ static void lt9211_atomic_disable(struct drm_bridge *bridge,
 	struct lt9211 *ctx = bridge_to_lt9211(bridge);
 	int ret;
 
-	if (ctx->chip_data->chip_type == LT9211C)
-		cancel_work_sync(&ctx->lt9211_work);
-
 	/*
 	 * Put the chip in reset, pull nRST line low,
 	 * and assure lengthy 10ms reset low timing.
@@ -1483,11 +1454,6 @@ static int lt9211_host_attach(struct lt9211 *ctx)
 	return 0;
 }
 
-static void lt9211_destroy_wq(void *data)
-{
-	destroy_workqueue(data);
-}
-
 static int lt9211_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
@@ -1532,17 +1498,6 @@ static int lt9211_probe(struct i2c_client *client)
 	if (ret)
 		return ret;
 
-	if (ctx->chip_data->chip_type == LT9211C) {
-		ctx->wq = create_workqueue("lt9211_work");
-		if (!ctx->wq)
-			return -ENOMEM;
-		/* Register after DSI attach so devres flushes work before freeing ctx->dsi. */
-		ret = devm_add_action_or_reset(dev, lt9211_destroy_wq, ctx->wq);
-		if (ret)
-			return ret;
-		INIT_WORK(&ctx->lt9211_work, lt9211_work_func);
-	}
-
 	return 0;
 }
 
-- 
2.47.3