linux-kernel - Re: [patch 1/8] PCI/MSI: Enable and mask MSIX early

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Message-ID: <87r1fjpkdc.ffs@nanos.tec.linutronix.de>
Date:   Tue, 27 Jul 2021 22:33:35 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        "Raj\, Ashok" <ashok.raj@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        Kevin Tian <kevin.tian@...el.com>,
        Marc Zyngier <maz@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        x86@...nel.org
Subject: Re: [patch 1/8] PCI/MSI: Enable and mask MSIX early

On Thu, Jul 22 2021 at 16:43, Bjorn Helgaas wrote:
> s/MSIX/MSI-X/ in subject

Sure.

> On Wed, Jul 21, 2021 at 09:11:27PM +0200, Thomas Gleixner wrote:
>> The ordering of MSI-X enable in hardware is disfunctional:
>
> s/disfunctional/dysfunctional/, isn't English wonderful ;)

Yes and I'm never going to master it.

>>  1) MSI-X is disabled in the control register
>>  2) Various setup functions
>>  3) pci_msi_setup_msi_irqs() is invoked which ends up accessing
>>     the MSI-X table entries
>>  4) MSI-X is enabled and masked in the control register with the
>>     comment that enabling is required for some hardware to access
>>     the MSI-X table
>> 
>> #4 obviously contradicts #3. The history of this is an issue with the NIU
>
> Annoyingly, if you "git rebase" and reword this commit log, it drops
> this line and the one a few lines below because they start with "#".
> Should be obvious, but took me a few iterations to see what was
> happening.

Cute.

Thanks,

        tglx