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

["David Rivshin (Allworx)" <drivshin.allworx@gmail.com>]

On Fri, 22 Apr 2016 16:03:34 +0300
Grygorii Strashko <grygorii.strashko@ti.com> wrote:

> On 04/21/2016 09:26 PM, David Rivshin (Allworx) wrote:
> > From: David Rivshin <drivshin@allworx.com>
> > 
> > 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 <drivshin@allworx.com>
> > Acked-by: Rob Herring <robh@kernel.org>
> > Tested-by: Nicolas Chauvet <kwizart@gmail.com>
> > ---
> > 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?

> 
> >   - 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.


> 
> 
> 
> >   		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;
> >   
> 
>