Re: "asix: Don't reset PHY on if_up for ASIX 88772" breaks net on arndale platform

[Charles Keepax <ckeepax@opensource.wolfsonmicro.com>]

On Tue, Nov 04, 2014 at 11:23:06AM +0100, Stam, Michel [FINT] wrote:
> Hello Riku,
> 
> >Fixing a bug (ethtool support) must not cause breakage elsewhere (in
> this case on arndale). This is now a regression of functionality from
> 3.17.
> >
> >I think it would better to revert the change now and with less hurry
> introduce a ethtool fix that doesn't break arndale.
> 
> I don't fully agree here; 
> I would like to point out that this commit is a revert itself. Fixing
> the armdale will then cause breakage in other implementations, such as
> ours. Blankly reverting breaks other peoples' implementations.
> 
> The PHY reset is the thing that breaks ethtool support, so any fix that
> appeases all would have to take existing PHY state into account. 
> 
> I'm not an expert on the ASIX driver, nor the MII, but I think this is
> the cause;
> drivers/net/usb/asix_devices.c:
>    361      asix_mdio_write(dev->net, dev->mii.phy_id, MII_BMCR,
> BMCR_RESET);
>    362      asix_mdio_write(dev->net, dev->mii.phy_id, MII_ADVERTISE,
>    363              ADVERTISE_ALL | ADVERTISE_CSMA);
>    364      mii_nway_restart(&dev->mii);
> 
> I would think that the ADVERTISE_ALL is the cause here, as it will reset
> the MII back to default, thus overriding ethtool settings.
> Would an:
> Int reg;
> reg = asix_mdio_read(dev->net,dev->mii.phy_id,MII_ADVERTISE);
> 
> prior to the offending lines, and then;
> 
>    362      asix_mdio_write(dev->net, dev->mii.phy_id, MII_ADVERTISE,
>    363             reg);
> 
> solve the problem for you guys?

If I revert the patch in question and add this in:

--- a/drivers/net/usb/asix_devices.c
+++ b/drivers/net/usb/asix_devices.c
@@ -299,6 +299,7 @@ static int ax88772_reset(struct usbnet *dev)
 {
        struct asix_data *data = (struct asix_data *)&dev->data;
        int ret, embd_phy;
+       int reg;
        u16 rx_ctl;

        ret = asix_write_gpio(dev,
@@ -359,8 +360,10 @@ static int ax88772_reset(struct usbnet *dev)
        msleep(150);

        asix_mdio_write(dev->net, dev->mii.phy_id, MII_BMCR, BMCR_RESET);
-       asix_mdio_write(dev->net, dev->mii.phy_id, MII_ADVERTISE,
-                       ADVERTISE_ALL | ADVERTISE_CSMA);
+       reg = asix_mdio_read(dev->net, dev->mii.phy_id, MII_ADVERTISE);
+       if (!reg)
+               reg = ADVERTISE_ALL | ADVERTISE_CSMA;
+       asix_mdio_write(dev->net, dev->mii.phy_id, MII_ADVERTISE, reg);
        mii_nway_restart(&dev->mii);

        ret = asix_write_medium_mode(dev, AX88772_MEDIUM_DEFAULT);

Then things work on Arndale for me. Does that work for you?
Whether that is a sensible fix I don't know however.

> 
> Mind, maybe the read function should take into account the reset value
> of the MII, and set it to ADVERTISE_ALL | ADVERTISE_CSMA. I don't have
> any documention here at the moment.

Yeah I also have no documentation.

Thanks,
Charles

> 
> Is anyone able to confirm my suspicions?
> 
> Kind regards,
> 
> Michel Stam
> -----Original Message-----
> From: Riku Voipio [mailto:riku.voipio@iki.fi] 
> Sent: Tuesday, November 04, 2014 10:44 AM
> To: Stam, Michel [FINT]
> Cc: Riku Voipio; davem@davemloft.net; linux-usb@vger.kernel.org;
> netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-samsung-soc@vger.kernel.org; ckeepax@opensource.wolfsonmicro.com
> Subject: Re: "asix: Don't reset PHY on if_up for ASIX 88772" breaks net
> on arndale platform
> 
> On Tue, Nov 04, 2014 at 09:19:26AM +0100, Stam, Michel [FINT] wrote:
> > Interesting, as the commit itself is a revert from a kernel back to 
> > 2.6 somewhere. The problem I had is related to the PHY being reset on 
> > interface-up, can you confirm that you require this?
> 
> I can't confirm what exactly is needed on arndale. I'm neither expert in
> USB or ethernet. However, I can confirm that without the PHY reset,
> networking doesn't work on arndale.
> 
> I now see someone else has the same problem, adding Charles to CC.
> 
> http://www.spinics.net/lists/linux-usb/msg116656.html
> 
> > Reverting this
> > breaks ethtool support in turn.
> 
> Fixing a bug (ethtool support) must not cause breakage elsewhere (in
> this case on arndale). This is now a regression of functionality from
> 3.17.
> 
> I think it would better to revert the change now and with less hurry
> introduce a ethtool fix that doesn't break arndale.
>  
> > Kind regards,
> > 
> > Michel Stam
> > 
> > -----Original Message-----
> > From: Riku Voipio [mailto:riku.voipio@iki.fi]
> > Sent: Tuesday, November 04, 2014 8:23 AM
> > To: davem@davemloft.net; Stam, Michel [FINT]
> > Cc: linux-usb@vger.kernel.org; netdev@vger.kernel.org; 
> > linux-kernel@vger.kernel.org; linux-samsung-soc@vger.kernel.org
> > Subject: "asix: Don't reset PHY on if_up for ASIX 88772" breaks net on
> 
> > arndale platform
> > 
> > Hi,
> > 
> > With 3.18-rc3, asix on arndale (samsung exynos 5250 based board), 
> > fails to work. Interface is initialized but network traffic seem not 
> > to pass through. With kernel IP config the result looks like:
> > 
> > [    3.323275] usb 3-3.2.4: new high-speed USB device number 4 using
> > exynos-ehci
> > [    3.419151] usb 3-3.2.4: New USB device found, idVendor=0b95,
> > idProduct=772a
> > [    3.424735] usb 3-3.2.4: New USB device strings: Mfr=1, Product=2,
> > SerialNumber=3
> > [    3.432196] usb 3-3.2.4: Product: AX88772 
> > [    3.436279] usb 3-3.2.4: Manufacturer: ASIX Elec. Corp.
> > [    3.441486] usb 3-3.2.4: SerialNumber: 000001
> > [    3.447530] asix 3-3.2.4:1.0 (unnamed net_device) (uninitialized):
> > invalid hw address, using random
> > [    3.764352] asix 3-3.2.4:1.0 eth0: register 'asix' at
> > usb-12110000.usb-3.2.4, ASIX AX88772 USB 2.0 Ethernet,
> de:a2:66:bf:ca:4f
> > [    4.488773] asix 3-3.2.4:1.0 eth0: link down
> > [    5.690025] asix 3-3.2.4:1.0 eth0: link up, 100Mbps, full-duplex,
> lpa
> > 0xC5E1
> > [    5.712947] Sending DHCP requests ...... timed out!
> > [   83.165303] IP-Config: Retrying forever (NFS root)...
> > [   83.170397] asix 3-3.2.4:1.0 eth0: link up, 100Mbps, full-duplex,
> lpa
> > 0xC5E1
> > [   83.192944] Sending DHCP requests .....
> > 
> > Similar results also with dhclient. Git bisect identified the breaking
> 
> > commit as:
> > 
> > commit 3cc81d85ee01e5a0b7ea2f4190e2ed1165f53c31
> > Author: Michel Stam <m.stam@fugro.nl>
> > Date:   Thu Oct 2 10:22:02 2014 +0200
> > 
> >     asix: Don't reset PHY on if_up for ASIX 88772
> > 
> > Taking 3.18-rc3 and that commit reverted, network works again:
> > 
> > [    3.303500] usb 3-3.2.4: new high-speed USB device number 4 using
> > exynos-ehci
> > [    3.399375] usb 3-3.2.4: New USB device found, idVendor=0b95,
> > idProduct=772a
> > [    3.404963] usb 3-3.2.4: New USB device strings: Mfr=1, Product=2,
> > SerialNumber=3
> > [    3.412424] usb 3-3.2.4: Product: AX88772 
> > [    3.416508] usb 3-3.2.4: Manufacturer: ASIX Elec. Corp.
> > [    3.421715] usb 3-3.2.4: SerialNumber: 000001
> > [    3.427755] asix 3-3.2.4:1.0 (unnamed net_device) (uninitialized):
> > invalid hw address, using random
> > [    3.744837] asix 3-3.2.4:1.0 eth0: register 'asix' at
> > usb-12110000.usb-3.2.4, ASIX AX88772 USB 2.0 Ethernet,
> 12:59:f1:a8:43:90
> > [    7.098998] asix 3-3.2.4:1.0 eth0: link up, 100Mbps, full-duplex,
> lpa
> > 0xC5E1
> > [    7.118258] Sending DHCP requests ., OK
> > [    9.753259] IP-Config: Got DHCP answer from 192.168.1.1, my address
> > is 192.168.1.111
> > 
> > There might something wrong on the samsung platform code (I understand
> 
> > the USB on arndale is "funny"), but this is still an regression from 
> > 3.17.
> > 
> > Riku