[PATCH 02/13] drm/ast: Test if I2C support has been initialized

From: Thomas Zimmermann <tzimmermann@suse.de>
To: airlied@redhat.com, daniel@ffwll.ch, sam@ravnborg.org,
	emil.l.velikov@gmail.com, kraxel@redhat.com,
	yc_chen@aspeedtech.com
Cc: Thomas Zimmermann <tzimmermann@suse.de>, dri-devel@lists.freedesktop.org
Subject: [PATCH 02/13] drm/ast: Test if I2C support has been initialized
Date: Tue, 28 Jul 2020 09:44:14 +0200	[thread overview]
Message-ID: <20200728074425.2749-3-tzimmermann@suse.de> (raw)
In-Reply-To: <20200728074425.2749-1-tzimmermann@suse.de>

The ast driver is supposed to work without I2C support. This is
tested by looking at the connector's i2c field being non-NULL.

After embedding the I2C structure in the connector, the i2c field
will not be a pointer. So change the test to look at the dev field
in struct ast_i2c_chan.

ast_get_modes() did not really test if I2C has been initialized, so
the patch adds this test as well.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/ast/ast_mode.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 19f1dfc8e9e0..45be020afcad 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -603,7 +603,6 @@ static struct ast_i2c_chan *ast_i2c_create(struct drm_device *dev)
 	i2c->adapter.owner = THIS_MODULE;
 	i2c->adapter.class = I2C_CLASS_DDC;
 	i2c->adapter.dev.parent = &dev->pdev->dev;
-	i2c->dev = dev;
 	i2c_set_adapdata(&i2c->adapter, i2c);
 	snprintf(i2c->adapter.name, sizeof(i2c->adapter.name),
 		 "AST i2c bit bus");
@@ -622,17 +621,30 @@ static struct ast_i2c_chan *ast_i2c_create(struct drm_device *dev)
 		goto out_free;
 	}
 
+	i2c->dev = dev; /* signals presence of I2C support */
+
 	return i2c;
 out_free:
 	kfree(i2c);
 	return NULL;
 }
 
-static void ast_i2c_destroy(struct ast_i2c_chan *i2c)
+static bool ast_i2c_is_initialized(struct ast_i2c_chan *i2c)
 {
-	if (!i2c)
+	return i2c && !!i2c->dev;
+}
+
+static void ast_i2c_fini(struct ast_i2c_chan *i2c)
+{
+	if (!ast_i2c_is_initialized(i2c))
 		return;
 	i2c_del_adapter(&i2c->adapter);
+	i2c->dev = NULL; /* clear to signal absence of I2C support */
+}
+
+static void ast_i2c_destroy(struct ast_i2c_chan *i2c)
+{
+	ast_i2c_fini(i2c);
 	kfree(i2c);
 }
 
@@ -1054,6 +1066,7 @@ static int ast_get_modes(struct drm_connector *connector)
 {
 	struct ast_connector *ast_connector = to_ast_connector(connector);
 	struct ast_private *ast = to_ast_private(connector->dev);
+	struct ast_i2c_chan *i2c = ast_connector->i2c;
 	struct edid *edid;
 	int ret;
 	bool flags = false;
@@ -1069,8 +1082,8 @@ static int ast_get_modes(struct drm_connector *connector)
 		else
 			kfree(edid);
 	}
-	if (!flags)
-		edid = drm_get_edid(connector, &ast_connector->i2c->adapter);
+	if (!flags && ast_i2c_is_initialized(i2c))
+		edid = drm_get_edid(connector, &i2c->adapter);
 	if (edid) {
 		drm_connector_update_edid_property(&ast_connector->base, edid);
 		ret = drm_add_edid_modes(connector, edid);
-- 
2.27.0

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