linux-kernel - Re: [Patch v7 6/7] irqchip: xilinx: Try to fall back if xlnx,kind-of-intr not provided

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Date:   Mon, 21 Nov 2016 14:17:26 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     monstr@...str.eu, jason@...edaemon.net,
        linux-kernel@...r.kernel.org, michal.simek@...inx.com,
        linuxppc-dev@...ts.ozlabs.org, mpe@...erman.id.au
Subject: Re: [Patch v7 6/7] irqchip: xilinx: Try to fall back if
 xlnx,kind-of-intr not provided

On 21/11/16 14:05, Zubair Lutfullah Kakakhel wrote:
> Hi,
> 
> On 11/18/2016 01:29 PM, Thomas Gleixner wrote:
>> On Mon, 14 Nov 2016, Zubair Lutfullah Kakakhel wrote:
>>
>>> The powerpc dts file does not have the xlnx,kind-of-intr property.
>>> Instead of erroring out, give a warning instead. And attempt to
>>> continue to probe the interrupt controller while assuming
>>> kind-of-intr is 0x0 as a fall back.
>>
>> This is broken, really. On multiplatform kernels this will try to probe the
>> chip no matter what.
> 
> I'm not sure I understand why this driver will probe on multi-platform kernels
> if the compatible string isn't in the DT?
> 
>>
>> Powerpc already has:
>>
>> static const struct of_device_id xilinx_intc_match[] __initconst = {
>>        { .compatible = "xlnx,opb-intc-1.00.c", },
>>        { .compatible = "xlnx,xps-intc-1.00.a", },
>>        {}
>> };
>>
>> Unless I'm missing something important, then adding those compatible
>> strings to the driver will just keep stuff working as expected instead of
>> adding unsafe and broken heuristics.
>>
> 
> The last two lines of the driver already specify the compatible strings.
> 
> "
> IRQCHIP_DECLARE(xilinx_intc_xps, "xlnx,xps-intc-1.00.a", xilinx_intc_of_init);
> IRQCHIP_DECLARE(xilinx_intc_opb, "xlnx,opb-intc-1.00.c", xilinx_intc_of_init);
> "

Is PPC actually using this infrastructure? It predates the whole
IRQCHIP_DECLARE business by about a decade. You seem to have tested it
using QEMU, so I assume it "just works", but I'd feel more reassured it
you stated so...

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...