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From:   Rui Salvaterra <rsalvaterra@gmail.com>
Date:   Thu, 7 Oct 2021 13:03:28 +0100
Message-ID: <CALjTZvbsvsD6abpw0H5D4ngUXPrgM2mDV0DX5BQi0z8cd-yxzA@mail.gmail.com>
Subject: Re: [REGRESSION][BISECTED] 5.15-rc1: Broken AHCI on NVIDIA ION (MCP79)
To:     Marc Zyngier <maz@kernel.org>
Cc:     tglx@linutronix.de, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Hi again, Marc,

On Thu, 7 Oct 2021 at 09:52, Marc Zyngier <maz@kernel.org> wrote:
>
[snipped]
>
> I guess this is the relevant device?

Pretty much, yes.

> It is interesting that it
> advertises not supporting interrupt masking... Can you, you, out of
> curiosity, give the following hack a go? I would expect things to
> behave badly too (and maybe be even worse). But one way or another, it
> may give us a hint.
>
> Thanks,
>
>         M.
>
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 0099a00af361..b3c0b9d07f17 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -205,7 +205,7 @@ static void __pci_msi_mask_desc(struct msi_desc *desc, u32 mask)
>
>         if (desc->msi_attrib.is_msix)
>                 pci_msix_mask(desc);
> -       else if (desc->msi_attrib.maskbit)
> +       else //if (desc->msi_attrib.maskbit)
>                 pci_msi_mask(desc, mask);
>  }
>
> @@ -216,7 +216,7 @@ static void __pci_msi_unmask_desc(struct msi_desc *desc, u32 mask)
>
>         if (desc->msi_attrib.is_msix)
>                 pci_msix_unmask(desc);
> -       else if (desc->msi_attrib.maskbit)
> +       else //if (desc->msi_attrib.maskbit)
>                 pci_msi_unmask(desc, mask);
>  }

Hm. You belive the controller is lying? :) Sure thing, I'll give it a
spin and let you know the result.

Thanks,
Rui