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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Marc Zyngier <maz@kernel.org>
Cc:     Frank Wunderlich <frank-w@public-files.de>,
        Ryder Lee <ryder.lee@mediatek.com>,
        linux-mediatek@lists.infradead.org,
        Frank Wunderlich <linux@fw-web.de>,
        linux-kernel@vger.kernel.org,
        Matthias Brugger <matthias.bgg@gmail.com>,
        linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: Aw: Re: [PATCH] pci: mediatek: fix warning in msi.h
In-Reply-To: <df5565a2f1e821041c7c531ad52a3344@kernel.org>
References: <20201031140330.83768-1-linux@fw-web.de> <878sbm9icl.fsf@nanos.tec.linutronix.de> <EC02022C-64CF-4F4B-A0A2-215A0A49E826@public-files.de> <87lfflti8q.wl-maz@kernel.org> <1604253261.22363.0.camel@mtkswgap22> <trinity-9eb2a213-f877-4af3-87df-f76a9c093073-1604255233122@3c-app-gmx-bap08> <87k0v4u4uq.wl-maz@kernel.org> <87pn4w90hm.fsf@nanos.tec.linutronix.de> <df5565a2f1e821041c7c531ad52a3344@kernel.org>
Date:   Mon, 02 Nov 2020 17:16:59 +0100
Message-ID: <87h7q791j8.fsf@nanos.tec.linutronix.de>
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On Mon, Nov 02 2020 at 11:30, Marc Zyngier wrote:
> On 2020-11-01 22:27, Thomas Gleixner wrote:
> The following patch makes it work for me (GICv3 guest without an ITS)by
> checking for the presence of an MSI domain at the point where we 
> actually
> perform this association, and before starting to scan for endpoints.
>
> I *think* this should work for the MTK thingy, but someone needs to
> go and check.
>
> Thanks,
>
>          M.
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 4289030b0fff..bb363eb103a2 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -871,6 +871,8 @@ static void pci_set_bus_msi_domain(struct pci_bus 
> *bus)
>   		d = pci_host_bridge_msi_domain(b);
>
>   	dev_set_msi_domain(&bus->dev, d);
> +	if (!d)
> +		bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;

Hrm, that might break legacy setups (no irqdomain support). I'd rather
prefer to explicitly tell the pci core at host registration time.

Bjorn?

Thanks,

        tglx