From:   Thomas Gleixner <tglx@linutronix.de>
To:     Will Deacon <will@kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <helgaas@kernel.org>,
        Marc Zygnier <maz@kernel.org>,
        Alex Williamson <alex.williamson@redhat.com>,
        Kevin Tian <kevin.tian@intel.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Megha Dey <megha.dey@intel.com>,
        Ashok Raj <ashok.raj@intel.com>, linux-pci@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Santosh Shilimkar <ssantosh@kernel.org>,
        iommu@lists.linux-foundation.org, dmaengine@vger.kernel.org,
        Stuart Yoder <stuyoder@gmail.com>,
        Laurentiu Tudor <laurentiu.tudor@nxp.com>,
        Nishanth Menon <nm@ti.com>, Tero Kristo <kristo@kernel.org>,
        linux-arm-kernel@lists.infradead.org, x86@kernel.org,
        Vinod Koul <vkoul@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Sinan Kaya <okaya@kernel.org>
Subject: Re: [patch 33/37] iommu/arm-smmu-v3: Use msi_get_virq()
In-Reply-To: <87lf17dsyp.ffs@tglx>
References: <20211126224100.303046749@linutronix.de>
 <20211126230525.885757679@linutronix.de>
 <20211129105506.GA22761@willie-the-truck> <87lf17dsyp.ffs@tglx>
Date:   Mon, 29 Nov 2021 13:58:46 +0100
Message-ID: <87ilwbdsop.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Mon, Nov 29 2021 at 13:52, Thomas Gleixner wrote:
> On Mon, Nov 29 2021 at 10:55, Will Deacon wrote:
>> On Sat, Nov 27, 2021 at 02:20:59AM +0100, Thomas Gleixner wrote:
>>> +	smmu->evtq.q.irq = msi_get_virq(dev, EVTQ_MSI_INDEX);
>>> +	smmu->gerr_irq = msi_get_virq(dev, GERROR_MSI_INDEX);
>>> +	smmu->priq.q.irq = msi_get_virq(dev, PRIQ_MSI_INDEX);
>>
>> Prviously, if retrieval of the MSI failed then we'd fall back to wired
>> interrupts. Now, I think we'll clobber the interrupt with 0 instead. Can
>> we make the assignments to smmu->*irq here conditional on the MSI being
>> valid, please?
>
> So the wired irq number is in ->irq already and MSI does an override
> if available. Not really obvious...

But, this happens right after:

     ret = platform_msi_domain_alloc_irqs(dev, nvec, arm_smmu_write_msi_msg);

So if that succeeded then the descriptors exist and have interrupts
assigned.

Thanks,

        tglx