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

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Date:   Mon, 5 Mar 2018 09:30:55 -0800
From:   Troy Kisky <troy.kisky@...ndarydevices.com>
To:     Guenter Roeck <linux@...ck-us.net>
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 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.
>>>
>>>
>>>   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
> 
It definitely was not noise. I bet it helps people searching the mailing list in the future.
Thanks for posting the resolution.

BR
Troy