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From:   Douglas Anderson <dianders@chromium.org>
To:     dri-devel@lists.freedesktop.org
Cc:     Daniel Vetter <daniel@ffwll.ch>,
        Javier Martinez Canillas <javierm@redhat.com>,
        robert.foss@linaro.org, lschyi@chromium.org,
        Sam Ravnborg <sam@ravnborg.org>, jjsu@chromium.org,
        Douglas Anderson <dianders@chromium.org>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        David Airlie <airlied@linux.ie>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/3] drm/bridge: ti-sn65dsi86: Use drm_bridge_connector
Date:   Fri,  4 Feb 2022 16:13:40 -0800
Message-Id: <20220204161245.v2.1.I3ab26b7f197cc56c874246a43e57913e9c2c1028@changeid>
In-Reply-To: <20220205001342.3155839-1-dianders@chromium.org>
References: <20220205001342.3155839-1-dianders@chromium.org>
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The ti-sn65dsi86 driver shouldn't hand-roll its own bridge
connector. It should use the normal drm_bridge_connector. Let's switch
to do that, removing all of the custom code.

NOTE: this still _doesn't_ implement DRM_BRIDGE_ATTACH_NO_CONNECTOR
support for ti-sn65dsi86 and that would still be a useful thing to do
in the future. It was attempted in the past [1] but put on the back
burner. However, unless we instantly change ti-sn65dsi86 fully from
not supporting DRM_BRIDGE_ATTACH_NO_CONNECTOR at all to _only_
supporting DRM_BRIDGE_ATTACH_NO_CONNECTOR then we'll still need a bit
of time when we support both. This is a better way to support the old
way where the driver hand rolls things itself.

A new notes about the implementation here:
* When using the drm_bridge_connector the connector should be created
  after all the bridges, so we change the ordering a bit.
* I'm reasonably certain that we don't need to do anything to "free"
  the new drm_bridge_connector. If drm_bridge_connector_init() returns
  success then we know drm_connector_init() was called with the
  `drm_bridge_connector_funcs`. The `drm_bridge_connector_funcs` has a
  .destroy() that does all the cleanup. drm_connector_init() calls
  __drm_mode_object_add() with a drm_connector_free() that will call
  the .destroy().
* I'm also reasonably certain that I don't need to "undo" the
  drm_bridge_attach() if drm_bridge_connector_init() fails. The
  "detach" function is private and other similar code doesn't try to
  undo the drm_bridge_attach() in error cases. There's also a comment
  indicating the lack of balance at the top of drm_bridge_attach().

[1] https://lore.kernel.org/r/20210920225801.227211-4-robdclark@gmail.com

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v2:
- ("ti-sn65dsi86: Use drm_bridge_connector") new for v2.

 drivers/gpu/drm/bridge/ti-sn65dsi86.c | 72 ++++++---------------------
 1 file changed, 14 insertions(+), 58 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index ba136a188be7..38616aab12ac 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -26,6 +26,7 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
+#include <drm/drm_bridge_connector.h>
 #include <drm/dp/drm_dp_aux_bus.h>
 #include <drm/dp/drm_dp_helper.h>
 #include <drm/drm_mipi_dsi.h>
@@ -174,7 +175,7 @@ struct ti_sn65dsi86 {
 	struct regmap			*regmap;
 	struct drm_dp_aux		aux;
 	struct drm_bridge		bridge;
-	struct drm_connector		connector;
+	struct drm_connector		*connector;
 	struct device_node		*host_node;
 	struct mipi_dsi_device		*dsi;
 	struct clk			*refclk;
@@ -646,54 +647,6 @@ static struct auxiliary_driver ti_sn_aux_driver = {
 	.id_table = ti_sn_aux_id_table,
 };
 
-/* -----------------------------------------------------------------------------
- * DRM Connector Operations
- */
-
-static struct ti_sn65dsi86 *
-connector_to_ti_sn65dsi86(struct drm_connector *connector)
-{
-	return container_of(connector, struct ti_sn65dsi86, connector);
-}
-
-static int ti_sn_bridge_connector_get_modes(struct drm_connector *connector)
-{
-	struct ti_sn65dsi86 *pdata = connector_to_ti_sn65dsi86(connector);
-
-	return drm_bridge_get_modes(pdata->next_bridge, connector);
-}
-
-static struct drm_connector_helper_funcs ti_sn_bridge_connector_helper_funcs = {
-	.get_modes = ti_sn_bridge_connector_get_modes,
-};
-
-static const struct drm_connector_funcs ti_sn_bridge_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 int ti_sn_bridge_connector_init(struct ti_sn65dsi86 *pdata)
-{
-	int ret;
-
-	ret = drm_connector_init(pdata->bridge.dev, &pdata->connector,
-				 &ti_sn_bridge_connector_funcs,
-				 DRM_MODE_CONNECTOR_eDP);
-	if (ret) {
-		DRM_ERROR("Failed to initialize connector with drm\n");
-		return ret;
-	}
-
-	drm_connector_helper_add(&pdata->connector,
-				 &ti_sn_bridge_connector_helper_funcs);
-	drm_connector_attach_encoder(&pdata->connector, pdata->bridge.encoder);
-
-	return 0;
-}
-
 /*------------------------------------------------------------------------------
  * DRM Bridge
  */
@@ -757,10 +710,6 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge,
 		return ret;
 	}
 
-	ret = ti_sn_bridge_connector_init(pdata);
-	if (ret < 0)
-		goto err_conn_init;
-
 	/* We never want the next bridge to *also* create a connector: */
 	flags |= DRM_BRIDGE_ATTACH_NO_CONNECTOR;
 
@@ -768,13 +717,20 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge,
 	ret = drm_bridge_attach(bridge->encoder, pdata->next_bridge,
 				&pdata->bridge, flags);
 	if (ret < 0)
-		goto err_dsi_host;
+		goto err_initted_aux;
+
+	pdata->connector = drm_bridge_connector_init(pdata->bridge.dev,
+						     pdata->bridge.encoder);
+	if (IS_ERR(pdata->connector)) {
+		ret = PTR_ERR(pdata->connector);
+		goto err_initted_aux;
+	}
+
+	drm_connector_attach_encoder(pdata->connector, pdata->bridge.encoder);
 
 	return 0;
 
-err_dsi_host:
-	drm_connector_cleanup(&pdata->connector);
-err_conn_init:
+err_initted_aux:
 	drm_dp_aux_unregister(&pdata->aux);
 	return ret;
 }
@@ -824,7 +780,7 @@ static void ti_sn_bridge_set_dsi_rate(struct ti_sn65dsi86 *pdata)
 
 static unsigned int ti_sn_bridge_get_bpp(struct ti_sn65dsi86 *pdata)
 {
-	if (pdata->connector.display_info.bpc <= 6)
+	if (pdata->connector->display_info.bpc <= 6)
 		return 18;
 	else
 		return 24;
-- 
2.35.0.263.gb82422642f-goog