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Subject: Re: lost interrupts when running sabrelite images (v4.15+) in qemu
To:     Troy Kisky <troy.kisky@boundarydevices.com>
Cc:     Fugang Duan <fugang.duan@nxp.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20180303163236.GA29514@roeck-us.net>
 <88917ab4-ade0-dcfc-e81a-eeaa8a4d15b8@boundarydevices.com>
From:   Guenter Roeck <linux@roeck-us.net>
Message-ID: <2801dae5-1334-a127-d36c-244d35e71222@roeck-us.net>
Date:   Sat, 3 Mar 2018 12:48:53 -0800
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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.

Thanks,
Guenter