From: Bjorn Helgaas <helgaas@kernel.org>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Amey Narkhede <ameynarkhede03@gmail.com>,
Oliver O'Halloran <oohall@gmail.com>,
Shanker R Donthineni <sdonthineni@nvidia.com>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-pci <linux-pci@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Sinan Kaya <okaya@kernel.org>, Vikram Sethi <vsethi@nvidia.com>
Subject: Re: [PATCH v4 2/2] PCI: Enable NO_BUS_RESET quirk for Nvidia GPUs
Date: Wed, 5 May 2021 15:40:16 -0500 [thread overview]
Message-ID: <20210505204016.GA1330808@bjorn-Precision-5520> (raw)
In-Reply-To: <20210505131357.07e55042@redhat.com>
On Wed, May 05, 2021 at 01:13:57PM -0600, Alex Williamson wrote:
> On Wed, 5 May 2021 23:10:32 +0530
> Amey Narkhede <ameynarkhede03@gmail.com> wrote:
> > On 21/05/05 01:56PM, Oliver O'Halloran wrote:
> > > On Wed, May 5, 2021 at 12:50 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > > > On Mon, May 03, 2021 at 09:07:11PM -0500, Shanker R Donthineni wrote:
> > > > > On 5/3/21 5:42 PM, Bjorn Helgaas wrote:
> > > > > > Obviously _RST only works for built-in devices, since there's no AML
> > > > > > for plug-in devices, right? So if there's a plug-in card with this
> > > > > > GPU, neither SBR nor _RST will work?
> > > > > These are not plug-in PCIe GPU cards, will exist on upcoming server
> > > > > baseboards. ACPI-reset should wok for plug-in devices as well as long
> > > > > as firmware has _RST method defined in ACPI-device associated with
> > > > > the PCIe hot-plug slot.
> > > >
> > > > Maybe I'm missing something, but I don't see how _RST can work for
> > > > plug-in devices. _RST is part of the system firmware, and that
> > > > firmware knows nothing about what will be plugged into the slot. So
> > > > if system firmware supplies _RST that knows how to reset the Nvidia
> > > > GPU, it's not going to do the right thing if you plug in an NVMe
> > > > device instead.
> > > >
> > > > Can you elaborate on how _RST would work for plug-in devices?
>
> I'm not sure I really understand these concerns about plug-in devices.
I'm not really concerned about plug-in devices. Shanker said above
that _RST would work for them:
ACPI-reset should work for plug-in devices as well as long as
firmware has _RST method defined in ACPI-device associated with the
PCIe hot-plug slot.
and I disagreed. _RST *cannot* work for plug-in devices because
firmware doesn't know what device will be plugged in and therefore
cannot provide the required device-specific _RST.
That's all I wanted to clarify.
Bjorn
next prev parent reply other threads:[~2021-05-05 20:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 0:49 [PATCH v4 1/2] PCI: Add support for a function level reset based on _RST method Shanker Donthineni
2021-04-29 0:49 ` [PATCH v4 2/2] PCI: Enable NO_BUS_RESET quirk for Nvidia GPUs Shanker Donthineni
2021-04-30 17:01 ` Bjorn Helgaas
2021-04-30 22:11 ` Shanker R Donthineni
2021-05-03 22:42 ` Bjorn Helgaas
2021-05-04 2:07 ` Shanker R Donthineni
2021-05-05 2:12 ` Bjorn Helgaas
2021-05-05 3:51 ` Shanker R Donthineni
2021-05-05 3:56 ` Oliver O'Halloran
2021-05-05 17:40 ` Amey Narkhede
2021-05-05 19:13 ` Alex Williamson
2021-05-05 20:04 ` Shanker R Donthineni
2021-05-05 20:40 ` Bjorn Helgaas [this message]
2021-05-05 12:15 ` Pali Rohár
2021-05-05 15:35 ` Shanker R Donthineni
2021-04-30 18:39 ` [PATCH v4 1/2] PCI: Add support for a function level reset based on _RST method Alex Williamson
2021-04-30 19:05 ` Shanker R Donthineni
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