Date:	Wed, 5 Nov 2014 14:39:37 +0200
From:	Riku Voipio <riku.voipio@....fi>
To:	"Stam, Michel [FINT]" <M.Stam@...ro.nl>
Cc:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>,
	davem@...emloft.net, linux-usb@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org
Subject: Re: "asix: Don't reset PHY on if_up for ASIX 88772" breaks net
 onarndale platform

Hi Michel,

On Wed, Nov 05, 2014 at 01:04:37PM +0100, Stam, Michel [FINT] wrote:
> After looking around I found the reset value for the 8772 chip, which
> seems to be 0x1E1 (ANAR register).
> 
> This equates to (according to include/uapi/linux/mii.h)
> ADVERTISE_ALL | ADVERTISE_CSMA.
> 
> The register only seems to become 0 if the software reset fails.
> 
> Unfortunately, this is exactly what I get when the patch is applied;
> asix 1-2:1.0 eth1: Failed to send software reset: ffffffb5
> asix 1-2:1.0 eth1: link reset failed (-75) usbnet usb-0000:00:1d.0-2, 
> ASIX AX88772 USB 2.0 Ethernet
> asix 1-2:1.0 eth1: Failed to send software reset: ffffffb5
> asix 1-2:1.0 eth1: link reset failed (-75) usbnet usb-0000:00:1d.0-2, 
> ASIX AX88772 USB 2.0 Ethernet
> 
> A little while after this its 'Failed to enable software MII access'.
> The ethernet device fails to see any link or accept any ethtool -s
> command.

> My device has vid:devid 0b95:772a (ASIX Elec. Corp.).

> Can you tell me what device is on the Andale platform, Charles? Same
> vendor/device id?

Bus 003 Device 004: ID 0b95:772a ASIX Electronics Corp. AX88772A Fast Ethernet

> Another thing that bothers me is that dev->mii.advertising seems to
> contain the same value, so maybe that can be used instead of a call to
> asix_mdio_read(). Can anyone comment on its purpose? Should it be a
> shadow copy of the real register or something?
 
> Riku, can you test Charles' patch as well?

With that patch + revert to ax88772_reset network works. I'm unable to get
ethtool to work with that patch or with the original 3.17 state of asix.
Once i disable autoneg network doesn't just work. 

> > >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.

My concern is, that none of us with this problem is a linux network
drivers expert. And no such expert joined the thread to help us. Thus if
we hurry to have proper fix for 3.18, our fix might easily be really
wrong.

Hence, it would seem safer to revert to 3.17 state before 3.18, so we
can propose a proper fix for 3.19. At least from our myopic view, having
no functioning net on arndale is worse than having non-functioning
ethtool (which doesn't seem to have bothered people for years).

Riku

> > 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@....fi]
> > Sent: Tuesday, November 04, 2014 10:44 AM
> > To: Stam, Michel [FINT]
> > Cc: Riku Voipio; davem@...emloft.net; linux-usb@...r.kernel.org; 
> > netdev@...r.kernel.org; linux-kernel@...r.kernel.org; 
> > linux-samsung-soc@...r.kernel.org; ckeepax@...nsource.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@....fi]
> > > Sent: Tuesday, November 04, 2014 8:23 AM
> > > To: davem@...emloft.net; Stam, Michel [FINT]
> > > Cc: linux-usb@...r.kernel.org; netdev@...r.kernel.org; 
> > > linux-kernel@...r.kernel.org; linux-samsung-soc@...r.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@...ro.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
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