linux-kernel - Re: [PATCH 0/2] Introduce PCI_FIXUP

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Date:   Mon, 22 Jun 2020 13:53:48 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Zhangfei Gao <zhangfei.gao@...aro.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Hanjun Guo <guohanjun@...wei.com>,
        Sudeep Holla <sudeep.holla@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        jean-philippe <jean-philippe@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        kenneth-lee-2012@...mail.com, Wangzhou <wangzhou1@...ilicon.com>,
        linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-acpi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 0/2] Introduce PCI_FIXUP_IOMMU

On Mon, Jun 01, 2020 at 12:41:04PM -0500, Bjorn Helgaas wrote:
> I found this [1] from Paul Menzel, which was a slowdown caused by
> quirk_usb_early_handoff().  I think the real problem is individual
> quirks that take a long time.
> 
> The PCI_FIXUP_IOMMU things we're talking about should be fast, and of
> course, they're only run for matching devices anyway.  So I'd rather
> keep them as PCI_FIXUP_FINAL than add a whole new phase.

Okay, so if it is not a performance problem, then I am fine with using
PCI_FIXUP_FINAL. But I dislike calling the fixups from IOMMU code, there
must be a better solution.


Regards,

	Joerg

> [1] https://lore.kernel.org/linux-pci/b1533fd5-1fae-7256-9597-36d3d5de9d2a@molgen.mpg.de/