Am Freitag, 11. März 2016, 15:56:04 schrieb Heiko Stübner:

Hi Caesar,

Am Freitag, 11. März 2016, 16:47:59 schrieb Sergei Shtylyov:

quoted

On 3/11/2016 1:55 PM, Caesar Wang wrote:

quoted

This patch adds to support the emac phy reset.

1) phy-reset-gpios:
The phy-reset-gpios is an optional property for arc emac device tree
boot.
Change the binding document to match the driver code.

2) phy-reset-duration:
Different boards may require different phy reset duration. Add property
phy-reset-duration for device tree probe, so that the boards that need
a longer reset duration can specify it in their device tree.

3) phy-reset-active-high:
We need that for a custom hardware that needs the reverse reset
sequence.

Of course, this patch will fix the issue on
https://patchwork.kernel.org/patch/8186801/.

In some cases, the emac couldn't work if you don't have reset the phy.
Let's add it to happy work.

Signed-off-by: Caesar Wang <redacted>
---

  drivers/net/ethernet/arc/emac_main.c | 41
  ++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+)

diff --git a/drivers/net/ethernet/arc/emac_main.c

b/drivers/net/ethernet/arc/emac_main.c index 6446af1..42384f6a 100644

--- a/drivers/net/ethernet/arc/emac_main.c
+++ b/drivers/net/ethernet/arc/emac_main.c

@@ -764,6 +764,45 @@ static const struct net_device_ops

arc_emac_netdev_ops = {>

  #endif
  };

+#ifdef CONFIG_OF
+static void emac_reset_phy(struct net_device *pdev)
+{
+	int err, phy_reset;
+	bool active_high = false;
+	int msec = 10;
+	struct device *dev = pdev->dev.parent;
+	struct device_node *np = dev->of_node;
+
+	if (!np)
+		return;
+
+	of_property_read_u32(np, "phy-reset-duration", &msec);
+	/* A sane reset duration should not be longer than 1s */
+	if (msec > 1000)
+		msec = 1;
+
+	phy_reset = of_get_named_gpio(np, "phy-reset-gpios", 0);
+	if (!gpio_is_valid(phy_reset))
+		return;
+
+	active_high = of_property_read_bool(np, "phy-reset-active-high");
+
+	err = devm_gpio_request_one(dev, phy_reset, active_high ?
+				    GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
+				    "phy-reset");
+	if (err) {
+		dev_err(dev, "failed to get phy-reset-gpios: %d\n", err);
+		return;
+	}
+	msleep(msec);
+	gpio_set_value_cansleep(phy_reset, !active_high);
+}

[...]

    Why not make it the mii_bus::reset() method? It gets called before the

MDIO bus scan.

while meddling with the emac, I've built some sort of preliminary variant of
Sergei's suggestion at [0] - maybe you could take a look for some sort of
inspiration ;-)

forgot to add ... of course the newer gpiod_* infrastructure should be used 
instead of the old integer-based gpio numbers

The code is lifted from the designware gmac driver, so the binding also is
similar.


Heiko


[0]
https://github.com/mmind/linux-rockchip/commit/a943c588783438ff1c508dfa8c79
f1709aa5775e