linux-kernel - Re: [PATCH] mmc: meson-gx: remove IRQF

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Date:   Wed, 07 Oct 2020 13:32:47 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Brad Harper <bjharper@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Kevin Hilman <khilman@...libre.com>,
        "open list\:ARM\/Amlogic Meson..." 
        <linux-amlogic@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "linux-mmc\@vger.kernel.org" <linux-mmc@...r.kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Marc Zyngier <maz@...nel.org>
Subject: Re: [PATCH] mmc: meson-gx: remove IRQF_ONESHOT


On Tue 06 Oct 2020 at 17:33, Thomas Gleixner <tglx@...utronix.de> wrote:

> Brad,
>
> On Wed, Oct 07 2020 at 00:45, Brad Harper wrote:
>> I'm happy to test anything on a range of amlogic hardware with standard 
>> / rt and  multiple mmc devices.  Ill test Jerome's patch in next 24 
>> hours to report the results.
>
> please do not top-post and trim your replies.
>
>> On 6/10/2020 11:43 pm, Thomas Gleixner wrote:
>>>       We rather should make interrupts which need to have their primary
>>>       handler in hard interrupt context to set IRQF_NO_THREAD. That
>>>       should at the same time confirm that the primary handler is RT
>>>       safe.
>>>
>>>       Let me stare at the core code and the actual usage sites some more.
>
> So there are a few nasties in there and I faintly remember that there
> was an assumption that interrupts which are requested with both a
> primary and a secondary handler should quiesce the device interrupt in
> the primary handler if needed. OTOH, this also enforces that the primary
> handler is RT safe, which is after a quick scan of all the usage sites
> not a given and quite some of the users rely on IRQF_ONESHOT.
>
> The below untested patch should cure the problem and keep the interrupt
> line masked if requested with IRQF_ONESHOT.
>

With arm64 defconfig on Khadas vim3, no obvious regression. Looks good.

Tested-by: Jerome Brunet <jbrunet@...libre.com>

I did not test with RT. Brad, Could you let us know is Thomas's patch
works for you ? Thx