Re: lost interrupts when running sabrelite images (v4.15+) in qemu

[Guenter Roeck]

On 03/05/2018 09:30 AM, Troy Kisky wrote:
> On 3/3/2018 1:12 PM, Guenter Roeck wrote:
> > On 03/03/2018 12:48 PM, Guenter Roeck wrote:
> > > On 03/03/2018 11:07 AM, Troy Kisky wrote:
> > > > On 3/3/2018 8:32 AM, Guenter Roeck wrote:
> > > > > Hi,
> > > > >
> > > > > since v4.15, I get the following runtime warning when running sabrelite images
> > > > > in qemu.
> > > > >
> > > > > irq 65: nobody cared (try booting with the "irqpoll" option)
> > > > > ...
> > > > > handlers:
> > > > > [<26292474>] fec_pps_interrupt
> > > > > Disabling IRQ #65
> > > > > fec 2188000.ethernet (unnamed net_device) (uninitialized): MDIO read timeout
> > > > >
> > > > > Bisect points to commit 4ad1ceec05e491 ("net: fec: Let fec_ptp have its
> > > > > own interrupt routine"). Analysis shows that platform_irq_count()
> > > > > returns 2, which is reduced to 1 by fec_enet_get_irq_cnt().
> > > > > If I let fec_enet_get_irq_cnt() return 2, the problem is gone.
> > > > > Reverting commit 4ad1ceec05e491 also fixes the problem.
> > > > >
> > > > > Bisect log is attached.
> > > >
> > > > Sounds like you found a bug with qemu. I just booted sabrelite over nfs fine.
> > > > My interrupts look like this.
> > > >
> > > >
> > > >  Â 64:ÂÂÂÂÂ 98767ÂÂÂÂÂÂÂÂÂ 0ÂÂÂÂÂÂÂÂÂ 0ÂÂÂÂÂÂÂÂÂ 0ÂÂÂÂ GIC-0 150 LevelÂÂÂÂ 2188000.ethernet
> > > >  Â 65:ÂÂÂÂÂÂÂÂÂ 0ÂÂÂÂÂÂÂÂÂ 0ÂÂÂÂÂÂÂÂÂ 0ÂÂÂÂÂÂÂÂÂ 0ÂÂÂÂ GIC-0 151 LevelÂÂÂÂ 2188000.ethernet
> > > > ___________
> > > > Irq 65 is only for ptp interrrupts now. If qemu is signaling an tx/rx frame interrupt on 65,
> > > > then qemu is wrong. Of course, I've never used qemu so feel free to ignore me if I make no sense.
> > >
> > > Thanks for checking with real hardware.
> > >
> > > This is what I see (with your patch reverted):
> > >
> > >  ÂÂ64:ÂÂÂÂÂÂÂÂÂ 0ÂÂÂÂ GIC-0 150 LevelÂÂÂÂ 2188000.ethernet
> > >  ÂÂ65:ÂÂÂÂÂÂÂÂ 64ÂÂÂÂ GIC-0 151 LevelÂÂÂÂ 2188000.ethernet
> > >
> > > Looking into the qemu source, I see:
> > >
> > > #define FSL_IMX6_ENET_MAC_1588_IRQ 118
> > > #define FSL_IMX6_ENET_MAC_IRQ 119
> > >
> > > FSL_IMX6_ENET_MAC_IRQ is then connected to fec interrupt index 0, and FSL_IMX6_ENET_MAC_1588_IRQ
> > > is connected to fec interrupt index 1.
> > >
> > > This may suggest that the defines are reversed. I'll see what happens if I swap them.
> >
> > Confirmed. If I swap the above defines, everything works fine. At the same time,
> > the modified qemu works with older kernels.
> >
> > Thanks a lot for the hint, and sorry for the noise.
> >
> > Guenter
> It definitely was not noise. I bet it helps people searching the mailing list in the future.
> Thanks for posting the resolution.

Turns out "works" as I stated above is not entirely accurate.

- v4.13 and later work
- In v4.12 and earlier, the Ethernet interface fails to instantiate with
	fec 2188000.ethernet (unnamed net_device) (uninitialized): MDIO read timeout
	fec: probe of 2188000.ethernet failed with error -5
  I have not found the reason yet. Unmodified qemu works fine.
- v4.1 and earlier crash. The crash is fixed by commit 32cba57ba74be ("net: fec:
  introduce fec_ptp_stop and use in probe fail path")

There is also a matching bug at lauchpad:

https://bugs.launchpad.net/qemu/+bug/1753309

Guenter