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From:   Frank Wunderlich <frank-w@public-files.de>
To:     Marc Zyngier <maz@kernel.org>
Cc:     linux-mediatek@lists.infradead.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Frank Wunderlich <linux@fw-web.de>,
        linux-kernel@vger.kernel.org, Ryder Lee <ryder.lee@mediatek.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
        chuanjia.liu@mediatek.com
Subject: Aw: Re: [PATCH] pci: mediatek: fix warning in msi.h
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Date:   Sun, 1 Nov 2020 16:58:26 +0100
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> Gesendet: Sonntag, 01. November 2020 um 12:43 Uhr
> Von: "Marc Zyngier" <maz@kernel.org>

> On Sun, 01 Nov 2020 09:25:04 +0000,
> Frank Wunderlich <frank-w@public-files.de> wrote:

> > It looks like for mt7623 there is no msi domain setup (done via
> > mtk_pcie_setup_irq callback + mtk_pcie_init_irq_domain) in mtk pcie
> > driver.
>
> Does this mean that this SoC never handled MSIs the first place? Which
> would explain the warning, as there is no MSI domain registered for
> the device, and we end-up falling back to arch_setup_msi_irqs().

i tried 5.10-rc1 (without my patch of course) on bananapi-r64 to check if =
driver
on mt7622 works better (this does setup a msi-domain in pcie-driver)....an=
d i got no warning.
so mt7623 needs to create an msi-domain or handle it in the correct way e.=
g.
by returning -ENOSPC like in your code.

> If this system truly is unable to handle MSIs, one potential
> workaround would be to register a PCI-MSI domain that would always
> fail its allocation with -ENOSPC. It is really ugly, but would keep
> the horror localised. See the patchlet below, which I can't test.
>
> If this situation is more common than we expect, we may need something
> in core code instead.

thanks for your code-example, here we need a response from MTK (CC'd Chuan=
jia Liu)

regards Frank