[PATCH 3/3] net: fec: Reset ethernet PHY whenever the enet_out clock is being enabled

Lothar Waßmann
2015-11-30T11:32:48Z

If a PHY uses ENET_OUT as reference clock, it may need a RESET to get
functional after the clock had been disabled.

Failure to do this results in the link state constantly toggling
between up and down:
fec 02188000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
fec 02188000.ethernet eth0: Link is Down
fec 02188000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
fec 02188000.ethernet eth0: Link is Down
[...]

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
---
drivers/net/ethernet/freescale/fec.h | 1 +
drivers/net/ethernet/freescale/fec_main.c | 46 ++++++++++++++++++++++++-------
2 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index 99d33e2..8ab4f7f 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -519,6 +519,7 @@ struct fec_enet_private {
int pause_flag;
int wol_flag;
u32 quirks;
+ struct gpio_desc *phy_reset;

struct napi_struct napi;
int csum_flags;
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 1a983fc..7ba2bbb 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -66,6 +66,7 @@

static void set_multicast_list(struct net_device *ndev);
static void fec_enet_itr_coal_init(struct net_device *ndev);
+static void fec_reset_phy(struct platform_device *pdev);

#define DRIVER_NAME "fec"

@@ -1861,6 +1862,8 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
ret = clk_prepare_enable(fep->clk_enet_out);
if (ret)
goto failed_clk_enet_out;
+
+ fec_reset_phy(fep->pdev);
}
if (fep->clk_ptp) {
mutex_lock(&fep->ptp_clk_mutex);
@@ -3231,13 +3234,32 @@ static int fec_enet_init(struct net_device *ndev)
}

#ifdef CONFIG_OF
-static void fec_reset_phy(struct platform_device *pdev)
+static struct gpio_desc *fec_get_reset_gpio(struct platform_device *pdev)
{
struct gpio_desc *phy_reset;
- int msec = 1;
struct device_node *np = pdev->dev.of_node;

if (!np)
+ return ERR_PTR(-ENODEV);
+
+ phy_reset = devm_gpiod_get_optional(&pdev->dev, "phy-reset",
+ GPIOD_OUT_LOW);
+ if (IS_ERR(phy_reset))
+ dev_err(&pdev->dev, "failed to get phy-reset-gpios: %ld\n",
+ PTR_ERR(phy_reset));
+ return phy_reset;
+}
+
+static void fec_reset_phy(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct net_device *ndev = platform_get_drvdata(pdev);
+ struct fec_enet_private *fep = netdev_priv(ndev);
+ int msec = 1;
+
+ if (!fep->phy_reset)
+ return;
+ if (!np)
return;

of_property_read_u32(np, "phy-reset-duration", &msec);
@@ -3245,17 +3267,16 @@ static void fec_reset_phy(struct platform_device *pdev)
if (msec > 1000)
msec = 1;

- phy_reset = devm_gpiod_get_optional(&pdev->dev, "phy-reset",
- GPIOD_OUT_LOW);
- if (IS_ERR(phy_reset)) {
- dev_err(&pdev->dev, "failed to get phy-reset-gpios: %ld\n",
- PTR_ERR(phy_reset));
- return;
- }
+ gpiod_set_value_cansleep(fep->phy_reset, 0);
msleep(msec);
- gpiod_set_value_cansleep(phy_reset, 1);
+ gpiod_set_value_cansleep(fep->phy_reset, 1);
}
#else /* CONFIG_OF */
+static void fec_get_reset_gpio(struct platform_device *pdev)
+{
+ return -EINVAL;
+}
+
static void fec_reset_phy(struct platform_device *pdev)
{
/*
@@ -3309,8 +3330,12 @@ fec_probe(struct platform_device *pdev)
struct device_node *np = pdev->dev.of_node, *phy_node;
int num_tx_qs;
int num_rx_qs;
+ struct gpio_desc *phy_reset;

fec_enet_get_queue_num(pdev, &num_tx_qs, &num_rx_qs);
+ phy_reset = fec_get_reset_gpio(pdev);
+ if (IS_ERR(phy_reset) && PTR_ERR(phy_reset) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;

/* Init network device */
ndev = alloc_etherdev_mqs(sizeof(struct fec_enet_private),
@@ -3331,6 +3356,7 @@ fec_probe(struct platform_device *pdev)
fep->netdev = ndev;
fep->num_rx_queues = num_rx_qs;
fep->num_tx_queues = num_tx_qs;
+ fep->phy_reset = phy_reset;

#if !defined(CONFIG_M5272)
/* default enable pause frame auto negotiation */
--
2.1.4