From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com>,
linux-pci@vger.kernel.org
Subject: Re: [PATCH v2] PCI/portdrv: Do not require an interrupt for all AER capable ports
Date: Thu, 8 Dec 2022 07:58:42 +0200 [thread overview]
Message-ID: <Y5F9EnsNqyc3hEeK@black.fi.intel.com> (raw)
In-Reply-To: <20221207223537.GA1480175@bhelgaas>
On Wed, Dec 07, 2022 at 04:35:37PM -0600, Bjorn Helgaas wrote:
> Hi Mika,
>
> On Wed, Dec 07, 2022 at 10:41:05AM +0200, Mika Westerberg wrote:
> > Only Root Ports and Event Collectors use MSI for AER. PCIe Switch ports
> > or endpoints on the other hand only send messages (that get collected by
> > the former). For this reason do not require PCIe switch ports and
> > endpoints to use interrupt if they support AER.
> >
> > This allows portdrv to attach PCIe switch ports of Intel DG1 and DG2
> > discrete graphics cards. These do not declare MSI or legacy interrupts.
>
> Help me understand more about this situation. I guess we want portdrv
> to attach not to a GPU itself, but to a switch port on the card that
> *leads* to the GPU?
Yes correct.
> >From the patch, it looks like the only PCIe port service this switch
> port advertises is AER (not PME, DPC, hotplug, etc), and it doesn't
> have MSI or MSI-X.
Correct.
> So aerdriver should be able to register for PCIE_PORT_SERVICE_AER, but
> aer_probe() ignores everything except Root Ports and RCECs. What's
> the benefit then? I must be missing something.
The portdrv is needed for power management and everything else PCI even
if there is no actual "service" attached.
next prev parent reply other threads:[~2022-12-08 5:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-07 8:41 [PATCH v2] PCI/portdrv: Do not require an interrupt for all AER capable ports Mika Westerberg
2022-12-07 14:31 ` Sathyanarayanan Kuppuswamy
2022-12-07 22:35 ` Bjorn Helgaas
2022-12-08 5:58 ` Mika Westerberg [this message]
2022-12-08 12:23 ` Bjorn Helgaas
2022-12-08 13:58 ` Mika Westerberg
2022-12-08 14:12 ` Mika Westerberg
2022-12-09 17:07 ` Bjorn Helgaas
2022-12-09 21:04 ` Sathyanarayanan Kuppuswamy
2022-12-09 21:48 ` Bjorn Helgaas
2022-12-09 22:13 ` Sathyanarayanan Kuppuswamy
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