linux-kernel - Re: [PATCH v2] genirq: add IRQF_NO_AUTOEN for request

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Date:   Thu, 7 Jan 2021 19:58:15 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Barry Song <song.bao.hua@...ilicon.com>
Cc:     tglx@...utronix.de, maz@...nel.org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, linuxarm@...neuler.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: Re: [PATCH v2] genirq: add IRQF_NO_AUTOEN for request_irq

On Tue, Jan 05, 2021 at 03:14:11PM +1300, Barry Song wrote:
> Many drivers don't want interrupts enabled automatically due to
> request_irq(). So they are handling this issue by either way of
> the below two:
> (1)
> irq_set_status_flags(irq, IRQ_NOAUTOEN);
> request_irq(dev, irq...);
> (2)
> request_irq(dev, irq...);
> disable_irq(irq);
> 
> The code in the second way is silly and unsafe. In the small time
> gap between request_irq() and disable_irq(), interrupts can still
> come.
> The code in the first way is safe though we might be able to do it
> in the generic irq code.
> 
> With this patch, drivers can request_irq with IRQF_NO_AUTOEN flag.
> They will need neither irq_set_status_flags() nor disable_irq().
> Hundreds of drivers with this problem will be handled afterwards.
> 
> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> Signed-off-by: Barry Song <song.bao.hua@...ilicon.com>

Can you also convert some in-kernel drivers to this new api so that we
can see how this works?

thanks,

greg k-h