Re: [net-next PATCH v7 02/16] net: phy: Introduce fwnode_mdio_find_device()

On Wed, Mar 10, 2021 at 10:50:57PM -0800, Saravana Kannan wrote:

On Wed, Mar 10, 2021 at 10:21 PM Calvin Johnson
[off-list ref] wrote:

quoted

Define fwnode_mdio_find_device() to get a pointer to the
mdio_device from fwnode passed to the function.

Refactor of_mdio_find_device() to use fwnode_mdio_find_device().

Signed-off-by: Calvin Johnson <redacted>
---

Changes in v7:
- correct fwnode_mdio_find_device() description

Changes in v6:
- fix warning for function parameter of fwnode_mdio_find_device()

Changes in v5: None
Changes in v4: None
Changes in v3: None
Changes in v2: None

 drivers/net/mdio/of_mdio.c   | 11 +----------
 drivers/net/phy/phy_device.c | 23 +++++++++++++++++++++++
 include/linux/phy.h          |  6 ++++++
 3 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/drivers/net/mdio/of_mdio.c b/drivers/net/mdio/of_mdio.c
index ea9d5855fb52..d5e0970b2561 100644
--- a/drivers/net/mdio/of_mdio.c
+++ b/drivers/net/mdio/of_mdio.c

@@ -347,16 +347,7 @@ EXPORT_SYMBOL(of_mdiobus_register);
  */
 struct mdio_device *of_mdio_find_device(struct device_node *np)
 {
-       struct device *d;
-
-       if (!np)
-               return NULL;
-
-       d = bus_find_device_by_of_node(&mdio_bus_type, np);
-       if (!d)
-               return NULL;
-
-       return to_mdio_device(d);
+       return fwnode_mdio_find_device(of_fwnode_handle(np));
 }
 EXPORT_SYMBOL(of_mdio_find_device);

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index cc38e326405a..daabb17bba00 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c

@@ -2819,6 +2819,29 @@ static bool phy_drv_supports_irq(struct phy_driver *phydrv)
        return phydrv->config_intr && phydrv->handle_interrupt;
 }

+/**
+ * fwnode_mdio_find_device - Given a fwnode, find the mdio_device
+ * @fwnode: pointer to the mdio_device's fwnode
+ *
+ * If successful, returns a pointer to the mdio_device with the embedded
+ * struct device refcount incremented by one, or NULL on failure.
+ * The caller should call put_device() on the mdio_device after its use.
+ */
+struct mdio_device *fwnode_mdio_find_device(struct fwnode_handle *fwnode)
+{
+       struct device *d;
+
+       if (!fwnode)
+               return NULL;
+
+       d = bus_find_device_by_fwnode(&mdio_bus_type, fwnode);

Sorry about the late review, but can you look into using
get_dev_from_fwnode()? As long as you aren't registering two devices
for the same fwnode, it's an O(1) operation instead of having to loop
through a list of devices in a bus. You can check the returned
device's bus type if you aren't sure about not registering two devices
with the same fw_node and then fall back to this looping.

I think it is better to keep it simple and clear with
bus_find_device_by_fwnode() instead of the additional code that comes
with get_dev_from_fwnode() until it has clear advantage over the former.

regards
Calvin