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Date: Thu, 28 Mar 2024 16:06:46 -0500
From: Bjorn Helgaas <helgaas@kernel.org>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: linux1394-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
	linux-pci@vger.kernel.org, edmund.raile@proton.me,
	Takashi Sakamoto <o-takashi@sakamocchi.jp>
Subject: Re: [PATCH v2] PCI: Mark LSI FW643 to avoid bus reset
Message-ID: <20240328210646.GA1581782@bhelgaas>
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On Thu, Mar 28, 2024 at 02:42:01PM -0600, Alex Williamson wrote:
> On Wed, 27 Mar 2024 10:01:19 -0500
> Bjorn Helgaas <helgaas@kernel.org> wrote:
> 
> > On Tue, Mar 26, 2024 at 10:18:58PM +0900, Takashi Sakamoto wrote:
> > > On Mon, Mar 25, 2024 at 09:41:49AM -0500, Bjorn Helgaas wrote:  
> > > > So even without this patch, you are able to pass the FW643 to a VM
> > > > with VFIO, and you don't see any issues caused by VFIO resetting the
> > > > device?  
> > >  
> > > Absolutely yes, at least in my VM, for recent years to maintain Linux
> > > FireWire subsystem and ALSA firewire stack.  
> > 
> > So there must be something different between your system and Edmund's.
> > Maybe we can refine the quirk so it avoids the SBR on Edmund's system
> > but not yours.
> > 
> > Can you both collect the output of "sudo lspci -vvv" so we can try to
> > figure out the difference?  Also a complete dmesg log would be helpful
> > and would contain DMI information that we might need if this is
> > firmware dependent.
> 
> The original patch proposed for this gave me the impression that this
> was a device used on various old Mac systems, not likely applicable to
> a general purpose plug-in card.  Given the expanded use case, I'd
> suggest reverting the patch.

Makes sense, I'll queue up a revert for v6.9 so we can take some time
to figure this out.

> I think we need significantly more exhaustive testing on the afflicted
> system to understand whether this is an issue with the endpoint, the
> root port, the BIOS, etc.
> 
> In the meantime, or maybe as a permanent solution, Edmund can make use
> of the reset_method interface in pci-syfs to restrict the available
> reset methods for the device rather than risk removing a reset
> mechanism identified as working by other users.  My 2 cents.  Thanks,
> 
> Alex
>