Date:   Thu, 24 Sep 2020 10:31:45 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     dri-devel@...ts.freedesktop.org, linux-samsung-soc@...r.kernel.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/bridge: tc358764: restore connector support

This patch restores DRM connector registration in the TC358764 bridge
driver and restores usage of the old drm_panel_* API, thus allows dynamic
panel registration. This fixes panel operation on Exynos5250-based
Arndale board.

This is equivalent to the revert of the following commits:
1644127f83bc "drm/bridge: tc358764: add drm_panel_bridge support"
385ca38da29c "drm/bridge: tc358764: drop drm_connector_(un)register"
and removal of the calls to drm_panel_attach()/drm_panel_detach(), which
were no-ops and has been removed in meanwhile.

Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
---
As I've reported and Andrzej Hajda pointed, the reverted patches break
operation of the panel on the Arndale board. Noone suggested how to fix
the regression, I've decided to send a revert until a new solution is
found.

The issues with tc358764 might be automatically resolved once the Exynos
DSI itself is converted to DRM bridge:
https://patchwork.kernel.org/cover/11770683/
but that approach has also its own issues so far.

Best regards,
Marek Szyprowski
---
 drivers/gpu/drm/bridge/tc358764.c | 107 +++++++++++++++++++++++++-----
 1 file changed, 92 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/bridge/tc358764.c b/drivers/gpu/drm/bridge/tc358764.c
index d89394bc5aa4..c1e35bdf9232 100644
--- a/drivers/gpu/drm/bridge/tc358764.c
+++ b/drivers/gpu/drm/bridge/tc358764.c
@@ -153,9 +153,10 @@ static const char * const tc358764_supplies[] = {
 struct tc358764 {
 	struct device *dev;
 	struct drm_bridge bridge;
+	struct drm_connector connector;
 	struct regulator_bulk_data supplies[ARRAY_SIZE(tc358764_supplies)];
 	struct gpio_desc *gpio_reset;
-	struct drm_bridge *panel_bridge;
+	struct drm_panel *panel;
 	int error;
 };
 
@@ -209,6 +210,12 @@ static inline struct tc358764 *bridge_to_tc358764(struct drm_bridge *bridge)
 	return container_of(bridge, struct tc358764, bridge);
 }
 
+static inline
+struct tc358764 *connector_to_tc358764(struct drm_connector *connector)
+{
+	return container_of(connector, struct tc358764, connector);
+}
+
 static int tc358764_init(struct tc358764 *ctx)
 {
 	u32 v = 0;
@@ -271,11 +278,43 @@ static void tc358764_reset(struct tc358764 *ctx)
 	usleep_range(1000, 2000);
 }
 
+static int tc358764_get_modes(struct drm_connector *connector)
+{
+	struct tc358764 *ctx = connector_to_tc358764(connector);
+
+	return drm_panel_get_modes(ctx->panel, connector);
+}
+
+static const
+struct drm_connector_helper_funcs tc358764_connector_helper_funcs = {
+	.get_modes = tc358764_get_modes,
+};
+
+static const struct drm_connector_funcs tc358764_connector_funcs = {
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.reset = drm_atomic_helper_connector_reset,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static void tc358764_disable(struct drm_bridge *bridge)
+{
+	struct tc358764 *ctx = bridge_to_tc358764(bridge);
+	int ret = drm_panel_disable(bridge_to_tc358764(bridge)->panel);
+
+	if (ret < 0)
+		dev_err(ctx->dev, "error disabling panel (%d)\n", ret);
+}
+
 static void tc358764_post_disable(struct drm_bridge *bridge)
 {
 	struct tc358764 *ctx = bridge_to_tc358764(bridge);
 	int ret;
 
+	ret = drm_panel_unprepare(ctx->panel);
+	if (ret < 0)
+		dev_err(ctx->dev, "error unpreparing panel (%d)\n", ret);
 	tc358764_reset(ctx);
 	usleep_range(10000, 15000);
 	ret = regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
@@ -296,28 +335,71 @@ static void tc358764_pre_enable(struct drm_bridge *bridge)
 	ret = tc358764_init(ctx);
 	if (ret < 0)
 		dev_err(ctx->dev, "error initializing bridge (%d)\n", ret);
+	ret = drm_panel_prepare(ctx->panel);
+	if (ret < 0)
+		dev_err(ctx->dev, "error preparing panel (%d)\n", ret);
+}
+
+static void tc358764_enable(struct drm_bridge *bridge)
+{
+	struct tc358764 *ctx = bridge_to_tc358764(bridge);
+	int ret = drm_panel_enable(ctx->panel);
+
+	if (ret < 0)
+		dev_err(ctx->dev, "error enabling panel (%d)\n", ret);
 }
 
 static int tc358764_attach(struct drm_bridge *bridge,
 			   enum drm_bridge_attach_flags flags)
+{
+	struct tc358764 *ctx = bridge_to_tc358764(bridge);
+	struct drm_device *drm = bridge->dev;
+	int ret;
+
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
+	ctx->connector.polled = DRM_CONNECTOR_POLL_HPD;
+	ret = drm_connector_init(drm, &ctx->connector,
+				 &tc358764_connector_funcs,
+				 DRM_MODE_CONNECTOR_LVDS);
+	if (ret) {
+		DRM_ERROR("Failed to initialize connector\n");
+		return ret;
+	}
+
+	drm_connector_helper_add(&ctx->connector,
+				 &tc358764_connector_helper_funcs);
+	drm_connector_attach_encoder(&ctx->connector, bridge->encoder);
+	ctx->connector.funcs->reset(&ctx->connector);
+	drm_connector_register(&ctx->connector);
+
+	return 0;
+}
+
+static void tc358764_detach(struct drm_bridge *bridge)
 {
 	struct tc358764 *ctx = bridge_to_tc358764(bridge);
 
-	return drm_bridge_attach(bridge->encoder, ctx->panel_bridge,
-				 bridge, flags);
+	drm_connector_unregister(&ctx->connector);
+	ctx->panel = NULL;
+	drm_connector_put(&ctx->connector);
 }
 
 static const struct drm_bridge_funcs tc358764_bridge_funcs = {
+	.disable = tc358764_disable,
 	.post_disable = tc358764_post_disable,
+	.enable = tc358764_enable,
 	.pre_enable = tc358764_pre_enable,
 	.attach = tc358764_attach,
+	.detach = tc358764_detach,
 };
 
 static int tc358764_parse_dt(struct tc358764 *ctx)
 {
-	struct drm_bridge *panel_bridge;
 	struct device *dev = ctx->dev;
-	struct drm_panel *panel;
 	int ret;
 
 	ctx->gpio_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
@@ -326,16 +408,12 @@ static int tc358764_parse_dt(struct tc358764 *ctx)
 		return PTR_ERR(ctx->gpio_reset);
 	}
 
-	ret = drm_of_find_panel_or_bridge(dev->of_node, 1, 0, &panel, NULL);
-	if (ret)
-		return ret;
-
-	panel_bridge = devm_drm_panel_bridge_add(dev, panel);
-	if (IS_ERR(panel_bridge))
-		return PTR_ERR(panel_bridge);
+	ret = drm_of_find_panel_or_bridge(ctx->dev->of_node, 1, 0, &ctx->panel,
+					  NULL);
+	if (ret && ret != -EPROBE_DEFER)
+		dev_err(dev, "cannot find panel (%d)\n", ret);
 
-	ctx->panel_bridge = panel_bridge;
-	return 0;
+	return ret;
 }
 
 static int tc358764_configure_regulators(struct tc358764 *ctx)
@@ -381,7 +459,6 @@ static int tc358764_probe(struct mipi_dsi_device *dsi)
 		return ret;
 
 	ctx->bridge.funcs = &tc358764_bridge_funcs;
-	ctx->bridge.type = DRM_MODE_CONNECTOR_LVDS;
 	ctx->bridge.of_node = dev->of_node;
 
 	drm_bridge_add(&ctx->bridge);
-- 
2.17.1

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