media: i2c: max9286: [Workaround] 'device is bound'
This introduces a local workaround to support multiple MAX9286 devices
on the same I2C bus.
Not for upstream consumption due to device_is_bound being an in kernel
symbol, and requires the module to be a built-in only.
Not-signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index b73884e..2491c68 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -154,6 +154,7 @@ struct max9286_priv {
struct media_pad pads[MAX9286_N_PADS];
struct regulator *regulator;
struct dentry *dbgroot;
+ bool poc_enabled;
struct gpio_chip gpio;
u8 gpio_state;
@@ -1172,12 +1173,22 @@ static int max9286_register_gpio(struct max9286_priv *priv)
return ret;
}
-static int max9286_init(struct device *dev)
+static const struct of_device_id max9286_dt_ids[] = {
+ { .compatible = "maxim,max9286" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, max9286_dt_ids);
+
+static int max9286_init(struct device *dev, void *data)
{
struct max9286_priv *priv;
struct i2c_client *client;
int ret;
+ /* Skip non-max9286 devices. */
+ if (!dev->of_node || !of_match_node(max9286_dt_ids, dev->of_node))
+ return 0;
+
client = to_i2c_client(dev);
priv = i2c_get_clientdata(client);
@@ -1188,6 +1199,8 @@ static int max9286_init(struct device *dev)
return ret;
}
+ priv->poc_enabled = true;
+
/*
* Regulator Workaround:
*
@@ -1233,10 +1246,30 @@ static int max9286_init(struct device *dev)
max9286_v4l2_unregister(priv);
err_regulator:
regulator_disable(priv->regulator);
+ priv->poc_enabled = false;
return ret;
}
+static int max9286_is_bound(struct device *dev, void *data)
+{
+ struct device *this = data;
+ int ret;
+
+ if (dev == this)
+ return 0;
+
+ /* Skip non-max9286 devices. */
+ if (!dev->of_node || !of_match_node(max9286_dt_ids, dev->of_node))
+ return 0;
+
+ ret = device_is_bound(dev);
+ if (!ret)
+ return -EPROBE_DEFER;
+
+ return 0;
+}
+
static void max9286_cleanup_dt(struct max9286_priv *priv)
{
struct max9286_source *source;
@@ -1388,16 +1421,26 @@ static int max9286_probe(struct i2c_client *client)
usleep_range(4000, 5000);
/*
- * The MAX9286 starts by default with all ports enabled, we disable all
- * ports early to ensure that all channels are disabled if we error out
- * and keep the bus consistent.
+ * We can have multiple MAX9286 instances on the same physical I2C
+ * bus, and I2C children behind ports of separate MAX9286 instances
+ * having the same I2C address. As the MAX9286 starts by default with
+ * all ports enabled, we need to disable all ports on all MAX9286
+ * instances before proceeding to further initialize the devices and
+ * instantiate children.
+ *
+ * Start by just disabling all channels on the current device. Then,
+ * if all other MAX9286 on the parent bus have been probed, proceed
+ * to initialize them all, including the current one.
*/
max9286_i2c_mux_close(priv);
/*
* The MAX9286 initialises with auto-acknowledge enabled by default.
- * This can be invasive to other transactions on the same bus, so
- * disable it early. It will be enabled only as and when needed.
+ * This means that if multiple MAX9286 devices are connected to an I2C
+ * bus, another MAX9286 could ack I2C transfers meant for a device on
+ * the other side of the GMSL links for this MAX9286 (such as a
+ * MAX9271). To prevent that disable auto-acknowledge early on; it
+ * will be enabled later as needed.
*/
max9286_configure_i2c(priv, false);
@@ -1422,10 +1465,21 @@ static int max9286_probe(struct i2c_client *client)
/* Add any userspace support before we return early. */
max9286_debugfs_init(priv);
- ret = max9286_init(&client->dev);
+ ret = device_for_each_child(client->dev.parent, &client->dev,
+ max9286_is_bound);
+ if (ret)
+ return 0;
+
+ dev_dbg(&client->dev,
+ "All max9286 probed: start initialization sequence\n");
+ ret = device_for_each_child(client->dev.parent, NULL,
+ max9286_init);
if (ret < 0)
goto err_cleanup_dt;
+ /* Leave the mux channels disabled until they are selected. */
+ max9286_i2c_mux_close(priv);
+
return 0;
err_cleanup_dt:
@@ -1448,7 +1502,8 @@ static int max9286_remove(struct i2c_client *client)
max9286_v4l2_unregister(priv);
- regulator_disable(priv->regulator);
+ if (priv->poc_enabled)
+ regulator_disable(priv->regulator);
gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
@@ -1457,12 +1512,6 @@ static int max9286_remove(struct i2c_client *client)
return 0;
}
-static const struct of_device_id max9286_dt_ids[] = {
- { .compatible = "maxim,max9286" },
- {},
-};
-MODULE_DEVICE_TABLE(of, max9286_dt_ids);
-
static struct i2c_driver max9286_i2c_driver = {
.driver = {
.name = "max9286",
