[PATCH net v2 2/3] drivers: net: cpsw: fix error messages when using phy-handle DT property

On Fri, 22 Apr 2016 16:03:34 +0300
Grygorii Strashko [off-list ref] wrote:

On 04/21/2016 09:26 PM, David Rivshin (Allworx) wrote:

quoted

From: David Rivshin <redacted>

The phy-handle, phy_id, and fixed-link properties are mutually exclusive,
and only one need be specified. However if phy-handle was specified, an
error message would complain about the lack of phy_id or fixed-link.

Also, if phy-handle was specified and the subsequent of_phy_connect()
failed, the error message still referenced slaved->data->phy_id, which
would be empty. Instead, use the name of the device_node as a useful
identifier.

Fixes: 9e42f715264f ("drivers: net: cpsw: add phy-handle parsing")
Signed-off-by: David Rivshin <redacted>
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Nicolas Chauvet <redacted>
---
If would like this for -stable it should apply cleanly as far back
as 4.5. It failes on 4.4 due to some context differences, but can be
applied with 'git am -C2'. Or, I can produce a separate patch against
linux-4.4.y if preferred.

Changes since v1 [1]:
- Rebased (no conflicts)
- Added Tested-by from Nicolas Chauvet
- Added Acked-by from Rob Herring for the binding change

[1] https://patchwork.ozlabs.org/patch/560324/

  Documentation/devicetree/bindings/net/cpsw.txt |  4 ++--
  drivers/net/ethernet/ti/cpsw.c                 | 17 +++++++++++++----
  2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/cpsw.txt b/Documentation/devicetree/bindings/net/cpsw.txt
index 28a4781..3033c0f 100644
--- a/Documentation/devicetree/bindings/net/cpsw.txt
+++ b/Documentation/devicetree/bindings/net/cpsw.txt

@@ -46,16 +46,16 @@ Optional properties:
  - dual_emac_res_vlan	: Specifies VID to be used to segregate the ports
  - mac-address		: See ethernet.txt file in the same directory
  - phy_id		: Specifies slave phy id  

May be the "phy_id" can be marked as deprecated? (while here)
The recommended property now is "phy-handle".

I can certainly do that. Perhaps something like this?
 - phy_id		: Specifies slave phy id (deprecated, use phy-handle)

Rob, would you have any issues with bundling that?

quoted

  - phy-handle		: See ethernet.txt file in the same directory
  
  Slave sub-nodes:
  - fixed-link		: See fixed-link.txt file in the same directory
-			  Either the property phy_id, or the sub-node
-			  fixed-link can be specified
+
+Note: Exactly one of phy_id, phy-handle, or fixed-link must be specified.
  
  Note: "ti,hwmods" field is used to fetch the base address and irq
  resources from TI, omap hwmod data base during device registration.
  Future plan is to migrate hwmod data base contents into device tree
  blob so that, all the required data will be used from device tree dts
  file.
  

diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index d69cb3f..3c81413 100644
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c

@@ -1150,16 +1150,19 @@ static void cpsw_slave_open(struct cpsw_slave *slave, struct cpsw_priv *priv)
  	if (slave->data->phy_node)
  		slave->phy = of_phy_connect(priv->ndev, slave->data->phy_node,
  				 &cpsw_adjust_link, 0, slave->data->phy_if);
  	else
  		slave->phy = phy_connect(priv->ndev, slave->data->phy_id,
  				 &cpsw_adjust_link, slave->data->phy_if);
  	if (IS_ERR(slave->phy)) {
-		dev_err(priv->dev, "phy %s not found on slave %d\n",
-			slave->data->phy_id, slave->slave_num);
+		dev_err(priv->dev, "phy \"%s\" not found on slave %d\n",
+			slave->data->phy_node ?
+				slave->data->phy_node->full_name :
+				slave->data->phy_id,
+			slave->slave_num);  

Unfortunately,  there are some inconsistency between legacy and FDT API :(
of_phy_connect() will return valid phy_device or NULL, but phy_connect()
can return valid phy_device or ERR_PTR().

Good catch, I hadn't noticed that. It looks like that's actually a more 
serious (pre-existing) bug: if of_phy_connect() returns NULL, we'd end 
up dereferencing it and pagefaulting.

How about moving the IS_ERR() check into the phy_connect() case like this:
	if (slave->data->phy_node) {
		slave->phy = of_phy_connect(priv->ndev, slave->data->phy_node,
				 &cpsw_adjust_link, 0, slave->data->phy_if);
	} else {
		slave->phy = phy_connect(priv->ndev, slave->data->phy_id,
				 &cpsw_adjust_link, slave->data->phy_if);
		if (IS_ERR(slave->phy))
			slave->phy = NULL;
	}
	if (!slave->phy) {
		dev_err(priv->dev, "phy \"%s\" not found on slave %d\n",
			slave->data->phy_node ?
				slave->data->phy_node->full_name :
				slave->data->phy_id,
			slave->slave_num);  
	} else {

Since you say the phy_id case is deprecated anyways, I'm not too concerned
about not printing the error code returned by phy_connect() in that case
(especially since it never did so in the past). That lets us still avoid
duplicating the dev_err() itself.

quoted

  		slave->phy = NULL;
  	} else {
  		phy_attached_info(slave->phy);
  
  		phy_start(slave->phy);
  
  		/* Configure GMII_SEL register */

@@ -2030,15 +2033,19 @@ static int cpsw_probe_dt(struct cpsw_platform_data *data,
  		/* This is no slave child node, continue */
  		if (strcmp(slave_node->name, "slave"))
  			continue;
  
  		slave_data->phy_node = of_parse_phandle(slave_node,
  							"phy-handle", 0);
  		parp = of_get_property(slave_node, "phy_id", &lenp);
-		if (of_phy_is_fixed_link(slave_node)) {
+		if (slave_data->phy_node) {
+			dev_dbg(&pdev->dev,
+				"slave[%d] using phy-handle=\"%s\"\n",
+				i, slave_data->phy_node->full_name);
+		} else if (of_phy_is_fixed_link(slave_node)) {
  			struct device_node *phy_node;
  			struct phy_device *phy_dev;
  
  			/* In the case of a fixed PHY, the DT node associated
  			 * to the PHY is the Ethernet MAC DT node.
  			 */
  			ret = of_phy_register_fixed_link(slave_node);

@@ -2067,15 +2074,17 @@ static int cpsw_probe_dt(struct cpsw_platform_data *data,
  			if (!mdio) {
  				dev_err(&pdev->dev, "Missing mdio platform device\n");
  				return -EINVAL;
  			}
  			snprintf(slave_data->phy_id, sizeof(slave_data->phy_id),
  				 PHY_ID_FMT, mdio->name, phyid);
  		} else {
-			dev_err(&pdev->dev, "No slave[%d] phy_id or fixed-link property\n", i);
+			dev_err(&pdev->dev,
+				"No slave[%d] phy_id, phy-handle, or fixed-link property\n",
+				i);
  			goto no_phy_slave;
  		}
  		slave_data->phy_if = of_get_phy_mode(slave_node);
  		if (slave_data->phy_if < 0) {
  			dev_err(&pdev->dev, "Missing or malformed slave[%d] phy-mode property\n",
  				i);
  			return slave_data->phy_if;