[PATCH] of/device: Don't register disabled devices

[PATCH] of/device: Don't register disabled devices

[Grant Likely]

Device nodes with the property status="disabled" are not usable and so
don't register them when parsing the device tree for devices.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Hollis Blanchard <hollis_blanchard@mentor.com>
Cc: Deepak Saxena <deepak_saxena@mentor.com>
Cc: Scott Wood <scottwood@freescale.com>,
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 drivers/of/platform.c |   22 ++++++++++++++--------
 1 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 5b4a07f..c01cd1a 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -633,6 +633,9 @@ EXPORT_SYMBOL(of_device_alloc);
  * @np: pointer to node to create device for
  * @bus_id: name to assign device
  * @parent: Linux device model parent device.
+ *
+ * Returns pointer to created platform device, or NULL if a device was not
+ * registered.  Unavailable devices will not get registered.
  */
 struct platform_device *of_platform_device_create(struct device_node *np,
 					    const char *bus_id,
@@ -640,6 +643,9 @@ struct platform_device *of_platform_device_create(struct device_node *np,
 {
 	struct platform_device *dev;
 
+	if (!of_device_is_available(np))
+		return NULL;
+
 	dev = of_device_alloc(np, bus_id, parent);
 	if (!dev)
 		return NULL;
@@ -683,8 +689,9 @@ static int of_platform_bus_create(const struct device_node *bus,
 		pr_debug("   create child: %s\n", child->full_name);
 		dev = of_platform_device_create(child, NULL, parent);
 		if (dev == NULL)
-			rc = -ENOMEM;
-		else if (!of_match_node(matches, child))
+			continue;
+
+		if (!of_match_node(matches, child))
 			continue;
 		if (rc == 0) {
 			pr_debug("   and sub busses\n");
@@ -733,10 +740,9 @@ int of_platform_bus_probe(struct device_node *root,
 	if (of_match_node(matches, root)) {
 		pr_debug(" root match, create all sub devices\n");
 		dev = of_platform_device_create(root, NULL, parent);
-		if (dev == NULL) {
-			rc = -ENOMEM;
+		if (dev == NULL)
 			goto bail;
-		}
+
 		pr_debug(" create all sub busses\n");
 		rc = of_platform_bus_create(root, matches, &dev->dev);
 		goto bail;
@@ -748,9 +754,9 @@ int of_platform_bus_probe(struct device_node *root,
 		pr_debug("  match: %s\n", child->full_name);
 		dev = of_platform_device_create(child, NULL, parent);
 		if (dev == NULL)
-			rc = -ENOMEM;
-		else
-			rc = of_platform_bus_create(child, matches, &dev->dev);
+			continue;
+
+		rc = of_platform_bus_create(child, matches, &dev->dev);
 		if (rc) {
 			of_node_put(child);
 			break;

Re: [PATCH] of/device: Don't register disabled devices

[Blanchard, Hollis]

On 01/03/2011 03:01 PM, Grant Likely wrote:
> Device nodes with the property status="disabled" are not usable and so
> don't register them when parsing the device tree for devices.
>
This is great and all, but a fair amount of driver code explicitly 
searches the tree, rather than registering a probe function. That's why 
our earlier patches in this area were more comprehensive.

What are your thoughts on handling those cases?

Hollis Blanchard
Mentor Graphics, Embedded Systems Division

> ---
>   drivers/of/platform.c |   22 ++++++++++++++--------
>   1 files changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 5b4a07f..c01cd1a 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -633,6 +633,9 @@ EXPORT_SYMBOL(of_device_alloc);
>    * @np: pointer to node to create device for
>    * @bus_id: name to assign device
>    * @parent: Linux device model parent device.
> + *
> + * Returns pointer to created platform device, or NULL if a device was not
> + * registered.  Unavailable devices will not get registered.
>    */
>   struct platform_device *of_platform_device_create(struct device_node *np,
>   					    const char *bus_id,
> @@ -640,6 +643,9 @@ struct platform_device *of_platform_device_create(struct device_node *np,
>   {
>   	struct platform_device *dev;
>
> +	if (!of_device_is_available(np))
> +		return NULL;
> +
>   	dev = of_device_alloc(np, bus_id, parent);
>   	if (!dev)
>   		return NULL;
> @@ -683,8 +689,9 @@ static int of_platform_bus_create(const struct device_node *bus,
>   		pr_debug("   create child: %s\n", child->full_name);
>   		dev = of_platform_device_create(child, NULL, parent);
>   		if (dev == NULL)
> -			rc = -ENOMEM;
> -		else if (!of_match_node(matches, child))
> +			continue;
> +
> +		if (!of_match_node(matches, child))
>   			continue;
>   		if (rc == 0) {
>   			pr_debug("   and sub busses\n");
> @@ -733,10 +740,9 @@ int of_platform_bus_probe(struct device_node *root,
>   	if (of_match_node(matches, root)) {
>   		pr_debug(" root match, create all sub devices\n");
>   		dev = of_platform_device_create(root, NULL, parent);
> -		if (dev == NULL) {
> -			rc = -ENOMEM;
> +		if (dev == NULL)
>   			goto bail;
> -		}
> +
>   		pr_debug(" create all sub busses\n");
>   		rc = of_platform_bus_create(root, matches,&dev->dev);
>   		goto bail;
> @@ -748,9 +754,9 @@ int of_platform_bus_probe(struct device_node *root,
>   		pr_debug("  match: %s\n", child->full_name);
>   		dev = of_platform_device_create(child, NULL, parent);
>   		if (dev == NULL)
> -			rc = -ENOMEM;
> -		else
> -			rc = of_platform_bus_create(child, matches,&dev->dev);
> +			continue;
> +
> +		rc = of_platform_bus_create(child, matches,&dev->dev);
>   		if (rc) {
>   			of_node_put(child);
>   			break;
>

Re: [PATCH] of/device: Don't register disabled devices

[David Gibson]

On Wed, Jan 05, 2011 at 02:53:27PM -0800, Blanchard, Hollis wrote:
> On 01/03/2011 03:01 PM, Grant Likely wrote:
> > Device nodes with the property status="disabled" are not usable and so
> > don't register them when parsing the device tree for devices.
> >
> This is great and all, but a fair amount of driver code explicitly 
> searches the tree, rather than registering a probe function. That's why 
> our earlier patches in this area were more comprehensive.
> 
> What are your thoughts on handling those cases?

One by one.  Trying to handle the explicit searches automagically is
just asking for trouble.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: [PATCH] of/device: Don't register disabled devices

[Grant Likely]

On Thu, Jan 06, 2011 at 10:35:35AM +1100, David Gibson wrote:
> On Wed, Jan 05, 2011 at 02:53:27PM -0800, Blanchard, Hollis wrote:
> > On 01/03/2011 03:01 PM, Grant Likely wrote:
> > > Device nodes with the property status="disabled" are not usable and so
> > > don't register them when parsing the device tree for devices.
> > >
> > This is great and all, but a fair amount of driver code explicitly 
> > searches the tree, rather than registering a probe function. That's why 
> > our earlier patches in this area were more comprehensive.

As your patch set shows, the total set isn't unmanageable, and the
preference for new code is to use the device model infrastructure if
at all possible.

> > 
> > What are your thoughts on handling those cases?
> 
> One by one.  Trying to handle the explicit searches automagically is
> just asking for trouble.

Just as David says, the special cases are... well... special.
Anything making decisions about registering devices needs to follow
the status!="okay" rules.

g.