From: Bjorn Helgaas <helgaas@kernel.org>
To: "Pali Rohár" <pali@kernel.org>
Cc: "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
"Marek Behún" <kabel@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] PCI: aardvark: Implement re-issuing config requests on CRS response
Date: Mon, 27 Sep 2021 11:23:48 -0500 [thread overview]
Message-ID: <20210927162348.GA650225@bhelgaas> (raw)
In-Reply-To: <20210926111319.sgtfsjovkhfkh4qs@pali>
On Sun, Sep 26, 2021 at 01:13:19PM +0200, Pali Rohár wrote:
> On Wednesday 22 September 2021 11:48:03 Bjorn Helgaas wrote:
> > The config read of Vendor ID after a reset should be done by the PCI
> > core, not a device driver.
>
> Of course. But in case of unexpected reset (which PCI code does not
> detect), card driver at the same time could issue some config read/write
> request.
By "unexpected reset", you mean a reset performed autonomously by the
device, or a reset initiated by the driver without help from the PCI
core? Either way, I think the PCI core is pretty much out of the
picture and the driver is on its own.
> > If we disable CRS SV, the only outcomes of
> > that read are:
> >
> > 1) Valid Vendor ID data, or
> >
> > 2) Failed transaction, typically reported as 0xffff data (and, I
> > expect, an Unsupported Request or similar error logged)
>
> Yes. And I think it should apply also for any other config register, not
> just vendor id.
Yes.
> In case error reporting or AER functionality is not supported then there
> would be no error logged. And PCI core / kernel does not have to know
> that such thing happened.
There *should* be at least the logging in Device Status for all PCIe
devices, though I'm not sure the PCI core handles that nicely. I'm
looking at PCIe r5.0, sec 6.2.5: https://imgur.com/a/0yqygiM
Bjorn
prev parent reply other threads:[~2021-09-27 16:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-23 12:02 [PATCH] PCI: aardvark: Implement re-issuing config requests on CRS response Pali Rohár
2021-09-10 23:13 ` Pali Rohár
2021-09-14 20:26 ` Bjorn Helgaas
2021-09-14 20:46 ` Pali Rohár
2021-09-14 20:55 ` Bjorn Helgaas
2021-09-15 10:55 ` Pali Rohár
2021-09-16 14:32 ` Bjorn Helgaas
2021-09-22 10:17 ` Pali Rohár
2021-09-22 16:48 ` Bjorn Helgaas
2021-09-26 11:13 ` Pali Rohár
2021-09-27 16:23 ` Bjorn Helgaas [this message]
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