Hi Florian,

On Thu, Sep 28, 2017 at 7:22 PM, Florian Fainelli [off-list ref] wrote:

On 09/28/2017 08:53 AM, Geert Uytterhoeven wrote:

quoted

If the optional "reset-gpios" property is specified in DT, the generic
MDIO bus code takes care of resetting the PHY during device probe.
However, the PHY may still have to be reset explicitly after system
resume.

This allows to restore Ethernet operation after resume from s2ram on
Salvator-XS, where the enable pin of the regulator providing PHY power
is connected to PRESETn, and PSCI suspend powers down the SoC.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/net/ethernet/renesas/ravb_main.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index fdf30bfa403bf416..96d1d48e302f8c9a 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c

@@ -19,6 +19,7 @@
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 #include <linux/if_vlan.h>
+#include <linux/gpio/consumer.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/module.h>

@@ -2268,6 +2269,7 @@ static int __maybe_unused ravb_resume(struct device *dev)
 {
      struct net_device *ndev = dev_get_drvdata(dev);
      struct ravb_private *priv = netdev_priv(ndev);
+     struct mii_bus *bus = priv->mii_bus;
      int ret = 0;

      if (priv->wol_enabled) {

@@ -2302,6 +2304,13 @@ static int __maybe_unused ravb_resume(struct device *dev)
       * reopen device if it was running before system suspended.
       */

+     /* PHY reset */
+     if (bus->reset_gpiod) {
+             gpiod_set_value_cansleep(bus->reset_gpiod, 1);
+             udelay(bus->reset_delay_us);
+             gpiod_set_value_cansleep(bus->reset_gpiod, 0);
+     }

This is a clever hack, but unfortunately this is also misusing the MDIO
bus reset line into a PHY reset line. As commented in patch 3, if this
reset line is tied to the PHY, then this should be a PHY property and

OK.

you cannot (ab)use the MDIO bus GPIO reset logic anymore...

And then I should add reset-gpios support to drivers/net/phy/micrel.c?
Or is there already generic code to handle per-PHY reset? I couldn't find it.

Should not you also try to manage this reset line during ravb_open() to
achiever better power savings?

I don't know. The Micrel KSZ9031RNXVA datasheet doesn't mention if it's
safe or not to assert reset for a prolonged time.

Thanks!

Gr{oetje,eeting}s,

                        Geert