net: stmmac: dwmac-meson8b: interface sometimes does not come up at boot

[Anand Moon]

Hi Jerome

On Mon, 13 Jun 2022 at 15:10, Jerome Brunet <jbrunet at baylibre.com> wrote:
>
>
> On Sat 11 Jun 2022 at 17:00, Da Xue <da at lessconfused.com> wrote:
>
> > On Wed, Mar 9, 2022 at 3:42 PM Heiner Kallweit <hkallweit1 at gmail.com> wrote:
> >
> >  On 09.03.2022 15:57, Jerome Brunet wrote:
> >  >
> >  > On Wed 09 Mar 2022 at 15:45, Erico Nunes <nunes.erico at gmail.com> wrote:
> >  >
> >  >> On Sun, Mar 6, 2022 at 1:56 PM Heiner Kallweit <hkallweit1 at gmail.com> wrote:
> >  >>> You could try the following (quick and dirty) test patch that fully mimics
> >  >>> the vendor driver as found here:
> >  >>> https://github.com/khadas/linux/blob/buildroot-aml-4.9/drivers/amlogic/ethernet/phy/amlogic.c
> >  >>>
> >  >>> First apply
> >  >>> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=a502a8f04097e038c3daa16c5202a9538116d563
> >  >>> This patch is in the net tree currently and should show up in linux-next
> >  >>> beginning of the week.
> >  >>>
> >  >>> On top please apply the following (it includes the test patch your working with).
> >  >>
> >  >> I triggered test jobs with this configuration (latest mainline +
> >  >> a502a8f0409 + test patch for vendor driver behaviour), and the results
> >  >> are pretty much the same as with the previous test patch from this
> >  >> thread only.
> >  >> That is, I never got the issue with non-functional link up anymore,
> >  >> but I get the (rare) issue with link not going up.
> >  >> The reproducibility is still extremely low, in the >1% range.
> >  >
> >  > Low reproducibility means the problem is still there, or at least not
> >  > understood completly.
> >  >
> >  > I understand the benefit from the user standpoint.
> >  >
> >  > Heiner if you are going to continue from the test patch you sent,
> >  > I would welcome some explanation with each of the changes.
> >  >
> >  The latest test patch was purely for checking whether we see any
> >  difference in behavior between vendor driver and the mainlined
> >  version. It's in no way meant to be applied to mainline.
> >
> >  > We know very little about this IP and I'm not very confortable with
> >  > tweaking/aligning with AML sdk "blindly" on a driver that has otherwise
> >  > been working well so far.
> >  >
> >
> >  This touches one thing I wanted to ask anyway: Supposedly Amlogic
> >  didn't develop an own Ethernet PHY, and if they licensed an existing
> >  IP then it should be similar to some other existing PHY (that may
> >  have a driver in phylib).
> >
> >  Then what I'll do is submit the following small change that brought
> >  the error rate significantly down according to Erico's tests.
> >
> >  -       phy_trigger_machine(phydev);
> >  +       if (irq_status & INTSRC_ANEG_COMPLETE)
> >  +               phy_queue_state_machine(phydev, msecs_to_jiffies(100));
> >  +       else
> >  +               phy_trigger_machine(phydev);
> >
> >  > Thx
> >  >
> >  >>
> >  >> So at this point, I'm not sure how much more effort to invest into
> >  >> this. Given the rate is very low and the fallback is it will just
> >  >> reset the link and proceed to work, I think the situation would
> >  >> already be much better with the solution from that test patch being
> >  >> merged. If you propose that as a patch separately, I'm happy to test
> >  >> the final submitted patch again and provide feedback there. Or if
> >  >> there is another solution to try, I can try with that too.
> >  >>
> >  >> Thanks
> >  >>
> >  >>
> >  >> Erico
> >  >
> >
> >  Heiner
> >
> > To help reproduce this problem, I have had this problem for as long as I can remember and it still occurs with this patch.
>
> Same here, on both gxl and g12a. Occurrence remains unchanged.
> The is even reproduced if the PHY is switched to polling mode so the
> merged change, related to the IRQ handling, is very unlikely to fix the
> problem.
>
> >
> > This doesn't happen on first boot most of the time. It happens on reboot consistently. I have tested with AML-S805X-CC board, AML-S905X-CC V1, and V2 boards.
> >
>
> On my side, I confirm the network never seems to get stuck in u-boot but
> it might break in Linux, even on the first boot after a power up from
> what I have seen so far.
>
> > I am on u-boot 22.04 with 5.18.3 which includes the patch.
> > u-boot brings up ethernet on start and can grab an IP.
> > Linux brings up ethernet and can grab an IP.
> > reboot
> > u-boot can grab an IP.
> > Linux does not get anything.
> > I have to do ip link set dev eth0 down && up once or more to get ethernet to work again.
> > Sometimes it spams meson8b-dwmac c9410000.ethernet eth0: Reset adapter. If it spams this, ethernet is dead and can't be recovered.
>
> I tried several things, none showing any improvement so far
> * Make sure LPI/EEE is disabled
> * Add the ethernet reset from the main controller on the MAC
> * Test the various DMA modes of STMMAC
> * Port the differences from u-boot and the vendor kernel in the Phy driver
>
> I have also tried to go back in time, up to v4.19 but the problem is actually
> already there. It occurs at lot less though.
> Since v5.6+ the occurence is quite high: approx 1 in 4 boots
> On v4.19: 1 in 50 boots - up to 150.
>
> >
>
> When the problem happen
> * link is reported up
> * ifconfig / MAC is claiming to be sending packets (Tx increasing - no Rx)
> * I see no traffic with wireshark
>
> The packets are getting lost somewhere. Can't say for sure if it is in
> the MAC or the PHY.
>
> > This is fixed via power cycle so I'm assuming some register is not reset or maybe the IP is stuck.
> >
>
> `ethtool -r eth0` also seems to work around the problem.
> This trigs the restart of so many things, it is close to an un/replug of
> the ethernet cable :/
>

Have you give a try for setting up a regulator for ethernet and
implementing runtime power management

Best Regards
-Anand
> > Best,
> > Da Xue
>
>
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