[PATCH v3 0/2] of: property: fw_devlink misc fixes

[PATCH v3 0/2] of: property: fw_devlink misc fixes

[Nicolas Saenz Julienne]

As I'm interested in using this feature to fine-tune Raspberry Pi 4's
device probe dependencies, I tried to get the board to boot with
fw_devlink=on. As of today's linux-next the board won't boot with that
option. I tried to address the underlying issues.

---
Changes since v2:
 - Address Saravana's comments

Changes since v1:
 - Address Saravana's comments
 - Drop patch #3 & #4


Nicolas Saenz Julienne (2):
  of: property: Fix create device links for all child-supplier
    dependencies
  of: property: Do not link to disabled devices

 drivers/of/property.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

-- 
2.26.0

[PATCH v3 1/2] of: property: Fix create device links for all child-supplier dependencies

[Nicolas Saenz Julienne]

Upon adding a new device from a DT node, we scan its properties and its
children's properties in order to create a consumer/supplier
relationship between the device and the property provider.

That said, it's possible for some of the node's children to be disabled,
which will create links that'll never be fulfilled.

To get around this, use the for_each_available_child_of_node() function
instead of for_each_available_node() when iterating over the node's
children.

Fixes: d4387cd11741 ("of: property: Create device links for all child-supplier depencencies")
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Saravana Kannan <saravanak@google.com>

---

Changes since v1:
 - Slightly reword description

 drivers/of/property.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index 252e4f6001553..dc034eb45defd 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1298,7 +1298,7 @@ static int of_link_to_suppliers(struct device *dev,
 		if (of_link_property(dev, con_np, p->name))
 			ret = -ENODEV;
 
-	for_each_child_of_node(con_np, child)
+	for_each_available_child_of_node(con_np, child)
 		if (of_link_to_suppliers(dev, child) && !ret)
 			ret = -EAGAIN;
 
-- 
2.26.0

Re: [PATCH v3 1/2] of: property: Fix create device links for all child-supplier dependencies

[Rob Herring]

On Mon, 20 Apr 2020 14:01:01 +0200, Nicolas Saenz Julienne wrote:
> Upon adding a new device from a DT node, we scan its properties and its
> children's properties in order to create a consumer/supplier
> relationship between the device and the property provider.
> 
> That said, it's possible for some of the node's children to be disabled,
> which will create links that'll never be fulfilled.
> 
> To get around this, use the for_each_available_child_of_node() function
> instead of for_each_available_node() when iterating over the node's
> children.
> 
> Fixes: d4387cd11741 ("of: property: Create device links for all child-supplier depencencies")
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> Reviewed-by: Saravana Kannan <saravanak@google.com>
> 
> ---
> 
> Changes since v1:
>  - Slightly reword description
> 
>  drivers/of/property.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Applied, thanks.

Rob

[PATCH v3 2/2] of: property: Do not link to disabled devices

[Nicolas Saenz Julienne]

When creating a consumer/supplier relationship between two devices,
make sure the supplier node is actually active. Otherwise this will
create a link relationship that will never be fulfilled. This, in the
worst case scenario, will hang the system during boot.

Note that, in practice, the fact that a device-tree represented
consumer/supplier relationship isn't fulfilled will not prevent devices
from successfully probing.

Fixes: a3e1d1a7f5fc ("of: property: Add functional dependency link from DT bindings")
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

---

Changes since v2:
 - Correct code comment
 - Use already available return handling code

Changes since v1:
 - Move availability check into the compatible search code and stop if
   node disabled

 drivers/of/property.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index dc034eb45defd..7bcf31ba717d8 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1045,8 +1045,20 @@ static int of_link_to_phandle(struct device *dev, struct device_node *sup_np,
 	 * Find the device node that contains the supplier phandle.  It may be
 	 * @sup_np or it may be an ancestor of @sup_np.
 	 */
-	while (sup_np && !of_find_property(sup_np, "compatible", NULL))
+	while (sup_np) {
+
+		/* Don't allow linking to a disabled supplier */
+		if (!of_device_is_available(sup_np)) {
+			of_node_put(sup_np);
+			sup_np = NULL;
+		}
+
+		if (of_find_property(sup_np, "compatible", NULL))
+			break;
+
 		sup_np = of_get_next_parent(sup_np);
+	}
+
 	if (!sup_np) {
 		dev_dbg(dev, "Not linking to %pOFP - No device\n", tmp_np);
 		return -ENODEV;
-- 
2.26.0

Re: [PATCH v3 2/2] of: property: Do not link to disabled devices

[Saravana Kannan]

On Mon, Apr 20, 2020 at 5:02 AM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> When creating a consumer/supplier relationship between two devices,
> make sure the supplier node is actually active. Otherwise this will
> create a link relationship that will never be fulfilled. This, in the
> worst case scenario, will hang the system during boot.
>
> Note that, in practice, the fact that a device-tree represented
> consumer/supplier relationship isn't fulfilled will not prevent devices
> from successfully probing.
>
> Fixes: a3e1d1a7f5fc ("of: property: Add functional dependency link from DT bindings")
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
>
> ---
>
> Changes since v2:
>  - Correct code comment
>  - Use already available return handling code
>
> Changes since v1:
>  - Move availability check into the compatible search code and stop if
>    node disabled
>
>  drivers/of/property.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index dc034eb45defd..7bcf31ba717d8 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -1045,8 +1045,20 @@ static int of_link_to_phandle(struct device *dev, struct device_node *sup_np,
>          * Find the device node that contains the supplier phandle.  It may be
>          * @sup_np or it may be an ancestor of @sup_np.
>          */
> -       while (sup_np && !of_find_property(sup_np, "compatible", NULL))
> +       while (sup_np) {
> +
> +               /* Don't allow linking to a disabled supplier */
> +               if (!of_device_is_available(sup_np)) {
> +                       of_node_put(sup_np);
> +                       sup_np = NULL;
> +               }
> +
> +               if (of_find_property(sup_np, "compatible", NULL))
> +                       break;
> +
>                 sup_np = of_get_next_parent(sup_np);
> +       }
> +
>         if (!sup_np) {
>                 dev_dbg(dev, "Not linking to %pOFP - No device\n", tmp_np);
>                 return -ENODEV;

Thanks for the fix!

Reviewed-by: Saravana Kannan <saravanak@google.com>

Re: [PATCH v3 2/2] of: property: Do not link to disabled devices

[Rob Herring]

On Mon, 20 Apr 2020 14:01:02 +0200, Nicolas Saenz Julienne wrote:
> When creating a consumer/supplier relationship between two devices,
> make sure the supplier node is actually active. Otherwise this will
> create a link relationship that will never be fulfilled. This, in the
> worst case scenario, will hang the system during boot.
> 
> Note that, in practice, the fact that a device-tree represented
> consumer/supplier relationship isn't fulfilled will not prevent devices
> from successfully probing.
> 
> Fixes: a3e1d1a7f5fc ("of: property: Add functional dependency link from DT bindings")
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> 
> ---
> 
> Changes since v2:
>  - Correct code comment
>  - Use already available return handling code
> 
> Changes since v1:
>  - Move availability check into the compatible search code and stop if
>    node disabled
> 
>  drivers/of/property.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 

Applied, thanks.

Rob