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

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Date:   Sat, 3 Mar 2018 13:12:23 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Troy Kisky <troy.kisky@...ndarydevices.com>
Cc:     Fugang Duan <fugang.duan@....com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: lost interrupts when running sabrelite images (v4.15+) in qemu

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.
>>
>>
>>   64:      98767          0          0          0     GIC-0 150 Level     2188000.ethernet
>>   65:          0          0          0          0     GIC-0 151 Level     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):
> 
>   64:          0     GIC-0 150 Level     2188000.ethernet
>   65:         64     GIC-0 151 Level     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