Re: [PATCH v3] net: sh_eth: do not advertise Gigabit capabilities when not available

[David Miller]

From: Thomas Petazzoni 
Date: Fri,  8 Dec 2017 16:35:40 +0100

> Not all variants of the sh_eth hardware have Gigabit
> support. Unfortunately, the current driver doesn't tell the PHY about
> the limited MAC capabilities. Due to this, if you have a Gigabit
> capable PHY, the PHY will advertise its Gigabit capability and
> establish a link at 1Gbit/s, even though the MAC doesn't support it.
> 
> In order to avoid this, we use the recently introduced
> phy_set_max_speed() to tell the PHY to not advertise speed higher than
> 100 MBit/s.
> 
> Tested on a SH7786 platform, with a Gigabit PHY.
> 
> Signed-off-by: Thomas Petazzoni 

Applied, thanks.

[PATCH v3] net: sh_eth: do not advertise Gigabit capabilities when not available

[Thomas Petazzoni]

Not all variants of the sh_eth hardware have Gigabit
support. Unfortunately, the current driver doesn't tell the PHY about
the limited MAC capabilities. Due to this, if you have a Gigabit
capable PHY, the PHY will advertise its Gigabit capability and
establish a link at 1Gbit/s, even though the MAC doesn't support it.

In order to avoid this, we use the recently introduced
phy_set_max_speed() to tell the PHY to not advertise speed higher than
100 MBit/s.

Tested on a SH7786 platform, with a Gigabit PHY.

Signed-off-by: Thomas Petazzoni 
---
Changes since v2:
 - Drop goto construction used in the phy_set_max_speed() error
   handling, as it is not needed. Suggested by Sergei Shtylyov.

Changes since v1:
 - Use phy_set_max_speed(), as suggested by Sergei Shtylyov
   .
---
 drivers/net/ethernet/renesas/sh_eth.c | 10 ++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/ethernet/renesas/sh_eth.c 
b/drivers/net/ethernet/renesas/sh_eth.c
index db72d13cebb9..75323000c364 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1892,6 +1892,16 @@ static int sh_eth_phy_init(struct net_device *ndev)
return PTR_ERR(phydev);
}
 
+   /* mask with MAC supported features */
+   if (mdp->cd->register_type != SH_ETH_REG_GIGABIT) {
+   int err = phy_set_max_speed(phydev, SPEED_100);
+   if (err) {
+   netdev_err(ndev, "failed to limit PHY to 100 Mbit/s\n");
+   phy_disconnect(phydev);
+   return err;
+   }
+   }
+
phy_attached_info(phydev);
 
return 0;
-- 
2.14.3