Re: [PATCH] net: bcmgenet: Return not supported if we don't have a WoL IRQ

[Florian Fainelli <f.fainelli@gmail.com>]

On 2/22/2022 12:07 PM, Peter Robinson wrote:
>> On 2/22/2022 1:53 AM, Peter Robinson wrote:
>>> The ethtool WoL enable function wasn't checking if the device
>>> has the optional WoL IRQ and hence on platforms such as the
>>> Raspberry Pi 4 which had working ethernet prior to the last
>>> fix regressed with the last fix, so also check if we have a
>>> WoL IRQ there and return ENOTSUPP if not.
>>>
>>> Fixes: 9deb48b53e7f ("bcmgenet: add WOL IRQ check")
>>> Fixes: 8562056f267d ("net: bcmgenet: request Wake-on-LAN interrupt")
>>> Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
>>> Suggested-by: Javier Martinez Canillas <javierm@redhat.com>
>>> ---
>>>    drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c | 4 ++++
>>>    1 file changed, 4 insertions(+)
>>>
>>> We're seeing this crash on the Raspberry Pi 4 series of devices on
>>> Fedora on 5.17-rc with the top Fixes patch and wired ethernet doesn't work.
>>
>> Are you positive these two things are related to one another? The
>> transmit queue timeout means that the TX DMA interrupt is not firing up
>> what is the relationship with the absence/presence of the Wake-on-LAN
>> interrupt line?
> 
> The first test I did was revert 9deb48b53e7f and the problem went
> away, then poked at a few bits and the patch also fixes it without
> having to revert the other fix. I don't know the HW well enough to
> know more.
> 
> It seems there's other fixes/improvements that could be done around
> WOL in the driver, the bcm2711 SoC at least in the upstream DT doesn't
> support/implement a WOL IRQ, yet the RPi4 reports it supports WOL.

There is no question we can report information more accurately and your 
patch fixes that.

> 
> This fix at least makes it work again in 5.17, I think improvements
> can be looked at later by something that actually knows their way
> around the driver and IP.

I happen to be that something, or rather consider myself a someone. But 
the DTS is perfectly well written and the Wake-on-LAN interrupt is 
optional, the driver assumes as per the binding documents that the 
Wake-on-LAN is the 3rd interrupt, when available.

What I was hoping to get at is the output of /proc/interrupts for the 
good and the bad case so we can find out if by accident we end-up not 
using the appropriate interrupt number for the TX path. Not that I can 
see how that would happen, but since we have had some interesting issues 
being reported before when mixing upstream and downstream DTBs, I just 
don't fancy debugging that again:

https://www.spinics.net/lists/arm-kernel/msg947308.html
-- 
Florian