linux-kernel - Re: [RFC PATCH] of: platform: Skip mapping of interrupts in of_device

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Message-ID: <875yry1316.wl-maz@kernel.org>
Date:   Thu, 09 Dec 2021 10:33:09 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [RFC PATCH] of: platform: Skip mapping of interrupts in of_device_alloc()

On Thu, 09 Dec 2021 10:00:44 +0000,
"Lad, Prabhakar" <prabhakar.csengg@...il.com> wrote:
> 
> > The root of the issue is that all the resource allocation is done
> > upfront, way before we even have a driver that could potentially
> > deal with this device. This is a potential waste of resource, and
> > it triggers the issue you noticed.
> >
> > If you delay the resource allocation until there is an actual
> > match with a driver, you could have a per-driver flag telling you
> > whether the IRQ allocation should be performed before the probe()
> > function is called.
> >
> As suggested by Rob, if we switch the drivers to use
> platform_get_resource(pdev, IORESOURCE_IRQ, n) call with
> platform_get_irq() this code should go away and with this switch the
> resource allocation will happen demand. Is this approach OK?

If you get rid of of_irq_to_resource_table() altogether, then yes,
this has a fighting chance to work.

	M.


-- 
Without deviation from the norm, progress is not possible.