netdev - Re: [PATCH] net: ks8851: Drop IRQ threading

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Message-ID: <7a50a241-0a93-3e44-bcc7-b9e07c62d616@denx.de>
Date:   Fri, 16 Dec 2022 23:19:27 +0100
From:   Marek Vasut <marex@...x.de>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Geoff Levand <geoff@...radead.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Petr Machata <petrm@...dia.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>
Subject: Re: [PATCH] net: ks8851: Drop IRQ threading

On 12/16/22 22:54, Dmitry Torokhov wrote:
> On Fri, Dec 16, 2022 at 02:23:04PM +0100, Eric Dumazet wrote:
>> On Fri, Dec 16, 2022 at 1:47 PM Marek Vasut <marex@...x.de> wrote:
>>>
>>> Request non-threaded IRQ in the KSZ8851 driver, this fixes the following warning:
>>> "
>>> NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!
>>
>> This changelog is a bit terse.
>>
>> Why can other drivers use request_threaded_irq(), but not this one ?
> 
> This one actually *has* to use threading, as (as far as I can see) the
> "lock" that is being taken in ks8851_irq for the SPI variant of the
> device is actually a mutex, so we have to be able to sleep in the
> interrupt handler...

So maybe we should use threaded one for the SPI variant and non-threaded 
one for the Parallel bus variant ?