Aw: Re: [PATCH] pci: mediatek: fix warning in msi.h

[Frank Wunderlich]

> Gesendet: Sonntag, 01. November 2020 um 12:43 Uhr
> Von: "Marc Zyngier" <maz at kernel.org>

> On Sun, 01 Nov 2020 09:25:04 +0000,
> Frank Wunderlich <frank-w at 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)....and 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 Chuanjia Liu)

regards Frank