Re: [PATCH] i2c: Mark instantiated device nodes with OF_POPULATE

Hi Guenter,

On Jan 15, 2015, at 20:55 , Guenter Roeck [off-list ref] wrote:

On Thu, Jan 15, 2015 at 08:33:18PM +0200, Pantelis Antoniou wrote:

quoted

Mark (and unmark) device nodes with the POPULATE flag as appropriate.
This is required to avoid multi probing when using I2C and device
overlays containing a mux.
This patch is also more careful with the release of the adapter device
which caused a deadlock with muxes, and does not break the build
on !OF since the node flag accessors are not defined then.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
---
drivers/i2c/i2c-core.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 39d25a8..1d44e3a 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c

@@ -1122,6 +1122,10 @@ EXPORT_SYMBOL_GPL(i2c_new_device);
 */

void i2c_unregister_device(struct i2c_client *client)
{
+#if IS_ENABLED(CONFIG_OF_DYNAMIC)

Hi Pantelis,

I thought I read a note somewhere a couple of days ago suggesting that
CONFIG_OF_DYNAMIC would go away soon. Also, of_node_clear_flag is defined
in #ifdef CONFIG_OF, and AFAICS none of the other callers set OF_POPULATED
in the context of CONFIG_OF_DYNAMIC. Given that, wouldn't it be better
to use CONFIG_OF ?

Thanks,
Guenter

Well, I thought about it. Thing is that the notifier is under CONFIG_DYNAMIC,
and it seems it’s natural to be that way.

When we move to always enabling CONFIG_DYNAMIC the change to CONFIG_OF will be
part of the conversion.

Regards

— Pantelis

quoted

+	if (client->dev.of_node)
+		of_node_clear_flag(client->dev.of_node, OF_POPULATED);
+#endif
	device_unregister(&client->dev);
}
EXPORT_SYMBOL_GPL(i2c_unregister_device);

@@ -1441,8 +1445,11 @@ static void of_i2c_register_devices(struct i2c_adapter *adap)

	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");

-	for_each_available_child_of_node(adap->dev.of_node, node)
+	for_each_available_child_of_node(adap->dev.of_node, node) {
+		if (of_node_test_and_set_flag(node, OF_POPULATED))
+			continue;
		of_i2c_register_device(adap, node);
+	}
}

static int of_dev_node_match(struct device *dev, void *data)

@@ -1976,6 +1983,11 @@ static int of_i2c_notify(struct notifier_block *nb, unsigned long action,

		if (adap == NULL)
			return NOTIFY_OK;	/* not for us */

+		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED)) {
+			put_device(&adap->dev);
+			return NOTIFY_OK;
+		}
+
		client = of_i2c_register_device(adap, rd->dn);
		put_device(&adap->dev);

@@ -1986,6 +1998,10 @@ static int of_i2c_notify(struct notifier_block *nb, unsigned long action,

		}
		break;
	case OF_RECONFIG_CHANGE_REMOVE:
+		/* already depopulated? */
+		if (!of_node_check_flag(rd->dn, OF_POPULATED))
+			return NOTIFY_OK;
+
		/* find our device by node */
		client = of_find_i2c_device_by_node(rd->dn);
		if (client == NULL)
-- 
1.7.12