Subject: Re: [PATCH V3 net-next 6/8] net: hns3: Add MDIO support to HNS3 Ethernet driver for hip08 SoC

From: Andrew Lunn <[email-masked]>
Date: Mon, 19 Jun 2017 05:52:44 +0200

On Sat, Jun 17, 2017 at 06:24:29PM +0100, Salil Mehta wrote:
> This patch adds the support of MDIO bus interface for HNS3 driver.
> Code provides various interfaces to start and stop the PHY layer
> and to read and write the MDIO bus or PHY.
> 
> Signed-off-by: Daode Huang <[email-masked]>
> Signed-off-by: lipeng <[email-masked]>
> Signed-off-by: Salil Mehta <[email-masked]>
> Signed-off-by: Yisen Zhuang <[email-masked]>
> ---
> Patch V3: Addressed Below comments:
>  1. Florian Fainelli: https://lkml.org/lkml/2017/6/13/963
>  2. Andrew Lunn: https://lkml.org/lkml/2017/6/13/1039

It is normal to say what you actually changed.

> Patch V2: Addressed below comments:
>  1. Florian Fainelli: https://lkml.org/lkml/2017/6/10/130
>  2. Andrew Lunn: https://lkml.org/lkml/2017/6/10/168
> Patch V1: Initial Submit
> ---
>  .../ethernet/hisilicon/hns3/hns3pf/hclge_mdio.c    | 249 +++++++++++++++++++++
>  1 file changed, 249 insertions(+)
>  create mode 100644 drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_mdio.c
> 
> diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_mdio.c b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_mdio.c
> new file mode 100644
> index 0000000..5b21c50
> --- /dev/null
> +++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_mdio.c
> @@ -0,0 +1,249 @@
> +/*
> + * Copyright (c) 2016~2017 Hisilicon Limited.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/etherdevice.h>
> +#include <linux/kernel.h>
> +
> +#include "hclge_cmd.h"
> +#include "hclge_main.h"
> +
> +enum hclge_mdio_c22_op_seq {
> +	HCLGE_MDIO_C22_WRITE = 1,
> +	HCLGE_MDIO_C22_READ = 2
> +};
> +
> +#define HCLGE_MDIO_CTRL_START_BIT       BIT(0)
> +#define HCLGE_MDIO_CTRL_ST_MSK  GENMASK(2, 1)
> +#define HCLGE_MDIO_CTRL_ST_LSH  1
> +#define HCLGE_MDIO_IS_C22(c22)  (((c22) << HCLGE_MDIO_CTRL_ST_LSH) & \
> +	HCLGE_MDIO_CTRL_ST_MSK)
> +
> +#define HCLGE_MDIO_CTRL_OP_MSK  GENMASK(4, 3)
> +#define HCLGE_MDIO_CTRL_OP_LSH  3
> +#define HCLGE_MDIO_CTRL_OP(access) \
> +	(((access) << HCLGE_MDIO_CTRL_OP_LSH) &	HCLGE_MDIO_CTRL_OP_MSK)
> +#define HCLGE_MDIO_CTRL_PRTAD_MSK       GENMASK(4, 0)
> +#define HCLGE_MDIO_CTRL_DEVAD_MSK       GENMASK(4, 0)

This all seems overly complex. How about

#define HCLGE_MDIO_CTRL_START_BIT       BIT(0)
#define HCLGE_MDIO_C22			BIT(1)
#define HCLGE_MDIO_WRITE		(1 << 3)
#define HCLGE_MDIO_READ			(2 << 3)
#define HCLGE_MDIO_C22_WRITE		(HCLGE_MDIO_CTRL_START_BIT | HCLGE_MDIO_C22 | HCLGE_MDIO_WRITE)
#define HCLGE_MDIO_C22_READ		(HCLGE_MDIO_CTRL_START_BIT | HCLGE_MDIO_C22 | HCLGE_MDIO_READ)
#define HCLGE_MDIO_C45_WRITE		(HCLGE_MDIO_CTRL_START_BIT | HCLGE_MDIO_WRITE)
#define HCLGE_MDIO_C45_READ		(HCLGE_MDIO_CTRL_START_BIT | HCLGE_MDIO_READ)

#define HCLGE_MDIO_STATUS_ERROR		BIT(0)

Keep it simple, don't have more defines than what you need.

> +static int hclge_mdio_write(struct mii_bus *bus, int phy_id, int regnum,
> +			    u16 data)
> +{
> +	struct hclge_dev *hdev = (struct hclge_dev *)bus->priv;
> +	struct hclge_mdio_cfg_cmd *mdio_cmd;
> +	enum hclge_cmd_status status;
> +	struct hclge_desc desc;
> +	u8 devad;
> +
> +	if (!bus)
> +		return -EINVAL;
> +
> +	devad = ((regnum >> 16) & 0x1f);

So you have changed this to only support C22. Which means devad is not
needed, since that is c45 only.

> +
> +	dev_dbg(&bus->dev, "phy id=%d, devad=%d\n", phy_id, devad);
> +
> +	hclge_cmd_setup_basic_desc(&desc, HCLGE_OPC_MDIO_CONFIG, false);
> +
> +	mdio_cmd = (struct hclge_mdio_cfg_cmd *)desc.data;
> +
> +	mdio_cmd->prtad = phy_id & HCLGE_MDIO_CTRL_PRTAD_MSK;
> +	mdio_cmd->data_wr = cpu_to_le16(data);
> +	mdio_cmd->devad = devad & HCLGE_MDIO_CTRL_DEVAD_MSK;
> +
> +	/* Write reg and data */
> +	mdio_cmd->ctrl_bit = HCLGE_MDIO_IS_C22(1);

Passing the parameter is now pointless if you are only doing C22.

> +	mdio_cmd->ctrl_bit |= HCLGE_MDIO_CTRL_OP(HCLGE_MDIO_C22_WRITE);
> +	mdio_cmd->ctrl_bit |= HCLGE_MDIO_CTRL_START_BIT;

Given the above defines, this now becomes

	mdio_cmd->ctrl_bit = HCLGE_MDIO_C22_WRITE;

> +
> +	status = hclge_cmd_send(&hdev->hw, &desc, 1);
> +	if (status) {
> +		dev_err(&hdev->pdev->dev,
> +			"mdio write fail when sending cmd, status is %d.\n",
> +			status);
> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +static int hclge_mdio_read(struct mii_bus *bus, int phy_id, int regnum)
> +{
> +	struct hclge_dev *hdev = (struct hclge_dev *)bus->priv;
> +	struct hclge_mdio_cfg_cmd *mdio_cmd;
> +	enum hclge_cmd_status status;
> +	struct hclge_desc desc;
> +	u8 devad;
> +
> +	if (!bus)
> +		return -EINVAL;
> +
> +	devad = ((regnum >> 16) & GENMASK(4, 0));
> +
> +	hclge_cmd_setup_basic_desc(&desc, HCLGE_OPC_MDIO_CONFIG, true);
> +
> +	mdio_cmd = (struct hclge_mdio_cfg_cmd *)desc.data;
> +
> +	dev_dbg(&bus->dev, "phy id=%d, devad=%d\n", phy_id, devad);

Generally, you would do this after the read has completed, so you can
include the value read.

> +
> +	mdio_cmd->prtad = phy_id & HCLGE_MDIO_CTRL_PRTAD_MSK;
> +	mdio_cmd->devad = devad & HCLGE_MDIO_CTRL_DEVAD_MSK;
> +
> +	/* Write reg and data */
> +	mdio_cmd->ctrl_bit = HCLGE_MDIO_IS_C22(1);
> +	mdio_cmd->ctrl_bit |= HCLGE_MDIO_CTRL_OP(HCLGE_MDIO_C22_WRITE);
> +	mdio_cmd->ctrl_bit |= HCLGE_MDIO_CTRL_START_BIT;
> +
> +	/* Read out phy data */
> +	status = hclge_cmd_send(&hdev->hw, &desc, 1);
> +	if (status) {
> +		dev_err(&hdev->pdev->dev,

Be consistent. With dev_dbg() you used bus->dev.

> +			"mdio read fail when get data, status is %d.\n",
> +			status);
> +		return status;
> +	}
> +
> +	if (HCLGE_MDIO_STA_VAL(mdio_cmd->sta)) {

  	if (mdio_cmd->status & HCLGE_MDIO_STATUS_ERROR) {

is much more readable.

> +		dev_err(&hdev->pdev->dev, "mdio read data error\n");
> +		return -EIO;
> +	}
> +
> +	return le16_to_cpu(mdio_cmd->data_rd);
> +}
> +
> +int hclge_mac_mdio_config(struct hclge_dev *hdev)
> +{
> +	struct hclge_mac *mac = &hdev->hw.mac;
> +	struct net_device *ndev = &mac->ndev;
> +	struct phy_device *phy_dev;

It is normal to call this phydev.

> +	struct mii_bus *mdio_bus;
> +	int ret;
> +
> +	if (hdev->hw.mac.phy_addr >= PHY_MAX_ADDR)
> +		return 0;
> +
> +	SET_NETDEV_DEV(ndev, &hdev->pdev->dev);

It seems odd doing this here. It is normally done in the probe()
function.

> +
> +	mdio_bus = devm_mdiobus_alloc(&hdev->pdev->dev);
> +	if (!mdio_bus) {
> +		ret = -ENOMEM;
> +		goto err_miibus_alloc;
> +	}
> +

Just
		return -ENOMEM;

> +	mdio_bus->name = "hisilicon MII bus";
> +	mdio_bus->read = hclge_mdio_read;
> +	mdio_bus->write = hclge_mdio_write;
> +	snprintf(mdio_bus->id, MII_BUS_ID_SIZE, "%s-%s", "mii",
> +		 dev_name(&hdev->pdev->dev));
> +
> +	mdio_bus->parent = &hdev->pdev->dev;
> +	mdio_bus->priv = hdev;
> +	mdio_bus->phy_mask = ~(1 << mac->phy_addr);
> +	ret = mdiobus_register(mdio_bus);
> +	if (ret) {
> +		dev_err(mdio_bus->parent,
> +			"Failed to register MDIO bus ret = %#x\n", ret);
> +		goto err_mdio_register;

If register failed, you don't want to call unregister.

> +	}
> +
> +	phy_dev = mdiobus_get_phy(mdio_bus, mac->phy_addr);
> +	if (!phy_dev || IS_ERR(phy_dev)) {
> +		dev_err(mdio_bus->parent, "Failed to get phy device\n");
> +		ret = -EIO;
> +		goto err_mdio_register;
> +	}
> +
> +	phy_dev->irq = mdio_bus->irq[mac->phy_addr];

The core will do this for you in phy_device_create().

> +	mac->phy_dev = phy_dev;

After you have attached the phydev to the netdev, you can use
ndev->phydev. It is better to use that, than keep it in the priv
structure.

> +
> +	return 0;
> +
> +err_mdio_register:
> +	mdiobus_unregister(mdio_bus);
> +	mdiobus_free(mdio_bus);

You allocated it using devm_mdiobus_alloc(). So this is going to cause
a double free of the memory.

> +err_miibus_alloc:
> +	return ret;
> +}
> +
> +static void hclge_mac_adjust_link(struct net_device *net_dev)

ndev is the most used name for the net_device.

> +{
> +	struct hclge_mac *hw_mac;
> +	struct hclge_dev *hdev;
> +	struct hclge_hw *hw;
> +	int duplex;
> +	int speed;
> +
> +	if (!net_dev)
> +		return;
> +
> +	hw_mac = container_of(net_dev, struct hclge_mac, ndev);
> +	hw = container_of(hw_mac, struct hclge_hw, mac);
> +	hdev = hw->back;
> +
> +	speed = hw_mac->phy_dev->speed;
> +	duplex = hw_mac->phy_dev->duplex;

speed = ndev->phydev->speed
duplex = ndev->phydev->duplex

> +
> +	/* update antoneg. */
> +	hw_mac->autoneg = hw_mac->phy_dev->autoneg;
> +
> +	if ((hw_mac->speed != speed) || (hw_mac->duplex != duplex))
> +		(void)hclge_cfg_mac_speed_dup(hdev, speed, !!duplex);
> +}
> +
> +int hclge_mac_start_phy(struct hclge_dev *hdev)
> +{
> +	struct hclge_mac *mac = &hdev->hw.mac;
> +	struct phy_device *phy_dev = mac->phy_dev;
> +	struct net_device *ndev = &mac->ndev;
> +	int ret;
> +
> +	if (!phy_dev)
> +		return 0;
> +
> +	phy_dev->dev_flags = 0;

It is pretty unusual to do this. So a comment would be good explaining
why it is needed.

> +
> +	ret = phy_connect_direct(ndev, phy_dev,
> +				 hclge_mac_adjust_link,
> +				 PHY_INTERFACE_MODE_SGMII);
> +	if (unlikely(ret)) {

If this was on the hotpath, handling 10 million packets per second,
using unlikely() might bring some benefit. But this function is only
going to be called once when the interface is opened. Don't use
unlikely().

> +		pr_info("phy_connect_direct err");

	netdev_dbg(ndev, "phy_connect_direct %d\n", ret);

> +		return -ENODEV;

Use the error code which phy_connect_direct() gave you.

> +	}
> +
> +	phy_dev->supported = SUPPORTED_10baseT_Half |
> +			SUPPORTED_10baseT_Full |
> +			SUPPORTED_100baseT_Half |
> +			SUPPORTED_100baseT_Full |
> +			SUPPORTED_Autoneg |
> +			SUPPORTED_1000baseT_Full;
> +

phydev->supported &= PHY_GBIT_FEATURES;

> +	phy_start(mac->phy_dev);

phy_start(ndev->phydev)

> +
> +	return 0;
> +}
> +
> +void hclge_mac_stop_phy(struct hclge_dev *hdev)
> +{
> +	if (!hdev->hw.mac.phy_dev)
> +		return;
> +
> +	phy_disconnect(hdev->hw.mac.phy_dev);
> +	phy_stop(hdev->hw.mac.phy_dev);

No need to call phy_stop() if you have called phy_disconnect():

/**
 * phy_disconnect - disable interrupts, stop state machine, and detach a PHY
 *                  device
 * @phydev: target phy_device struct
 */

 Andrew