Subject: Re: [RFC net-next PATCH v2 2/2] net: dpaa2-mac: Add ACPI support for DPAA2 MAC driver

From: Russell King - ARM Linux admin <[email-masked]>
Date: Sat, 18 Apr 2020 12:38:13 +0100

On Sat, Apr 18, 2020 at 04:24:32PM +0530, Calvin Johnson wrote:
> Modify dpaa2_mac_connect() to support ACPI along with DT.
> Modify dpaa2_mac_get_node() to get the dpmac fwnode from either
> DT or ACPI.
> Replace of_get_phy_mode with fwnode_get_phy_mode to get
> phy-mode for a dpmac_node.
> Define and use helper functions fwnode_phy_match() and
> fwnode_phy_find_device() to find phy_dev that is later
> connected to mac->phylink.
> 
> Signed-off-by: Calvin Johnson <[email-masked]>
> ---
> 
> Changes in v2:
> - Major change following other network drivers supporting ACPI
> - dropped v1 patches 1, 2, 4, 5 and 6 as they are no longer valid
> - incorporated other v1 review comments
> 
>  .../net/ethernet/freescale/dpaa2/dpaa2-mac.c  | 122 ++++++++++++++----
>  1 file changed, 94 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
> index 3ee236c5fc37..5a03da54a67f 100644
> --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
> +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
> @@ -3,6 +3,9 @@
>  
>  #include "dpaa2-eth.h"
>  #include "dpaa2-mac.h"
> +#include <linux/acpi.h>
> +#include <linux/phy.h>
> +#include <linux/phylink.h>

Why do you need linux/phy.h and linux/phylink.h here?  Please try
building the driver without; you'll find they are already included
via dpaa2-mac.h.

> +static int fwnode_phy_match(struct device *dev, const void *phy_fwnode)
> +{
> +	return dev->fwnode == phy_fwnode;
> +}
> +
> +static struct phy_device *fwnode_phy_find_device(struct fwnode_handle *phy_fwnode)
> +{
> +	struct device *d;
> +	struct mdio_device *mdiodev;
> +
> +	if (!phy_fwnode)
> +		return NULL;
> +
> +	d = bus_find_device(&mdio_bus_type, NULL, phy_fwnode, fwnode_phy_match);
> +	if (d) {
> +		mdiodev = to_mdio_device(d);
> +		if (mdiodev->flags & MDIO_DEVICE_FLAG_PHY)
> +			return to_phy_device(d);
> +		put_device(d);
> +	}
> +
> +	return NULL;
> +}

This is groping around in the mdio bus implementation details; drivers
must not do this layering violation.  Please propose an interface in
the mdio code to do what you need.

> +
>  int dpaa2_mac_connect(struct dpaa2_mac *mac)
>  {
>  	struct fsl_mc_device *dpmac_dev = mac->mc_dev;
>  	struct net_device *net_dev = mac->net_dev;
> -	struct device_node *dpmac_node;
> +	struct fwnode_handle *dpmac_node = NULL;
> +	struct fwnode_reference_args args;
> +	struct phy_device *phy_dev;
>  	struct phylink *phylink;
>  	struct dpmac_attr attr;
> +	int status;
>  	int err;
>  
>  	err = dpmac_open(mac->mc_io, 0, dpmac_dev->obj_desc.id,
> @@ -251,7 +299,7 @@ int dpaa2_mac_connect(struct dpaa2_mac *mac)
>  
>  	mac->if_link_type = attr.link_type;
>  
> -	dpmac_node = dpaa2_mac_get_node(attr.id);
> +	dpmac_node = dpaa2_mac_get_node(&mac->mc_dev->dev, attr.id);
>  	if (!dpmac_node) {
>  		netdev_err(net_dev, "No dpmac@%d node found.\n", attr.id);
>  		err = -ENODEV;
> @@ -269,7 +317,7 @@ int dpaa2_mac_connect(struct dpaa2_mac *mac)
>  	 * error out if the interface mode requests them and there is no PHY
>  	 * to act upon them
>  	 */
> -	if (of_phy_is_fixed_link(dpmac_node) &&
> +	if (of_phy_is_fixed_link(to_of_node(dpmac_node)) &&
>  	    (mac->if_mode == PHY_INTERFACE_MODE_RGMII_ID ||
>  	     mac->if_mode == PHY_INTERFACE_MODE_RGMII_RXID ||
>  	     mac->if_mode == PHY_INTERFACE_MODE_RGMII_TXID)) {
> @@ -282,7 +330,7 @@ int dpaa2_mac_connect(struct dpaa2_mac *mac)
>  	mac->phylink_config.type = PHYLINK_NETDEV;
>  
>  	phylink = phylink_create(&mac->phylink_config,
> -				 of_fwnode_handle(dpmac_node), mac->if_mode,
> +				 dpmac_node, mac->if_mode,
>  				 &dpaa2_mac_phylink_ops);
>  	if (IS_ERR(phylink)) {
>  		err = PTR_ERR(phylink);
> @@ -290,20 +338,38 @@ int dpaa2_mac_connect(struct dpaa2_mac *mac)
>  	}
>  	mac->phylink = phylink;
>  
> -	err = phylink_of_phy_connect(mac->phylink, dpmac_node, 0);
> +	if (is_of_node(dpmac_node))
> +		err = phylink_of_phy_connect(mac->phylink,
> +					     to_of_node(dpmac_node), 0);
> +	else if (is_acpi_node(dpmac_node)) {
> +		status = acpi_node_get_property_reference(dpmac_node,
> +							  "phy-handle",
> +							  0, &args);
> +		if (ACPI_FAILURE(status))
> +			goto err_phylink_destroy;
> +		phy_dev = fwnode_phy_find_device(args.fwnode);
> +		if (!phy_dev)
> +			goto err_phylink_destroy;
> +
> +		err = phylink_connect_phy(mac->phylink, phy_dev);
> +		if (err)
> +			phy_detach(phy_dev);

phy_detach() reverses the effect of phy_attach_direct().  This is not
the correct cleanup function in this case, because the PHY hasn't been
attached (and phylink_connect_phy() will clean up any effects it has
on error.)  You only need to reverse the effect of your
fwnode_phy_find_device(), which phy_detach() is inappropriate for.

In any case, if this method of getting a PHY is accepted by ACPI folk,
it could be moved into a helper in phylink_fwnode_phy_connect() - and
that really needs to happen before a patch adding this functionality is
acceptable.

> +	}
>  	if (err) {
> -		netdev_err(net_dev, "phylink_of_phy_connect() = %d\n", err);
> +		netdev_err(net_dev, "phylink_fwnode_phy_connect() = %d\n", err);

That's a very misleading change - there is no function named as per your
new name.

>  		goto err_phylink_destroy;
>  	}
>  
> -	of_node_put(dpmac_node);
> +	if (is_of_node(dpmac_node))
> +		of_node_put(to_of_node(dpmac_node));
>  
>  	return 0;
>  
>  err_phylink_destroy:
>  	phylink_destroy(mac->phylink);
>  err_put_node:
> -	of_node_put(dpmac_node);
> +	if (is_of_node(dpmac_node))
> +		of_node_put(to_of_node(dpmac_node));
>  err_close_dpmac:
>  	dpmac_close(mac->mc_io, 0, dpmac_dev->mc_handle);
>  	return err;
> -- 
> 2.17.1
> 
> 

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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