linux-kernel - Re: [PATCH] irqchip: Skip contexts other supervisor in plic

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Message-ID: <alpine.DEB.2.21.9999.1910231917340.2470@viisi.sifive.com>
Date:   Wed, 23 Oct 2019 19:21:32 -0700 (PDT)
From:   Paul Walmsley <paul.walmsley@...ive.com>
To:     Alan Mikhak <alan.mikhak@...ive.com>
cc:     linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        tglx@...utronix.de, jason@...edaemon.net, maz@...nel.org,
        Palmer Dabbelt <palmer@...ive.com>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH] irqchip: Skip contexts other supervisor in plic_init()

On Wed, 23 Oct 2019, Alan Mikhak wrote:

> On Wed, Oct 23, 2019 at 11:54 AM Paul Walmsley <paul.walmsley@...ive.com> wrote:
> > On Wed, 23 Oct 2019, Alan Mikhak wrote:
> >
> > > Modify plic_init() to skip .dts interrupt contexts other
> > > than supervisor external interrupt.
> >
> > Might be good to explain the motivation here.
> 
> The .dts entry for plic may specify multiple interrupt contexts. For example,
> it may assign two entries IRQ_M_EXT and IRQ_S_EXT, in that order, to
> the same interrupt controller. This patch modifies plic_init() to skip the
> IRQ_M_EXT context since IRQ_S_EXT is currently the only supported
> context.
> 
> If IRQ_M_EXT is not skipped, plic_init() will report "handler already
> present for context" when it comes across the IRQ_S_EXT context
> in the next iteration of its loop.
> 
> Without this patch, .dts would have to be edited to replace the
> value of IRQ_M_EXT with -1 for it to be skipped.
> 
> I will add the above explanation in a v2 patch description, if it
> sounds reasonable.

Thanks, that explanation sounds good; and sounds like Christoph will 
flow with this change as well.  So with the description expanded as 
you plan to, feel free to add an

Acked-by: Paul Walmsley <paul.walmsley@...ive.com> # arch/riscv 


- Paul