From: Bjorn Helgaas <helgaas@kernel.org>
To: "Z.q. Hou" <zhiqiang.hou@nxp.com>
Cc: Rob Herring <robh@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
PCI <linux-pci@vger.kernel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
Michael Walle <michael@walle.cc>,
Ard Biesheuvel <ardb@kernel.org>
Subject: Re: [PATCH] PCI: dwc: Added link up check in map_bus of dw_child_pcie_ops
Date: Fri, 18 Sep 2020 07:47:10 -0500 [thread overview]
Message-ID: <20200918124710.GA1800067@bjorn-Precision-5520> (raw)
In-Reply-To: <HE1PR0402MB3371F8191538F47E8249F048843F0@HE1PR0402MB3371.eurprd04.prod.outlook.com>
On Fri, Sep 18, 2020 at 11:02:07AM +0000, Z.q. Hou wrote:
> But now the SError is exactly caused by the first access of the
> non-existent function, I dug into the kernel enumeration code and
> found it will fire a 4Byte CFG read transaction to read the Vendor
> ID and Device ID together, so I suspect the root cause is access the
> Device ID of a non-existent function triggers SError.
>
> So the alternative solution seems to correct the PCIe enumeration, I
> will submit a patch to let the first access only read the Vendor ID.
If it is incorrect for the first access to be a 32-bit read of both
the Vendor and the Device ID, please cite the relevant section of the
spec in your patch.
I don't like to make changes to generic code to accommodate specific
pieces of hardware because then we restrict future changes based on
some device that will soon be obsolete and forgotten.
I'm pretty sure the spec language about CRS handling is careful to
talk about "reads that *include* Vendor ID", not just "reads of Vendor
ID", so the implication is that it covers 32-bit reads as well as
16-bit reads.
Bjorn
next prev parent reply other threads:[~2020-09-18 12:47 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 5:41 [PATCH] PCI: dwc: Added link up check in map_bus of dw_child_pcie_ops Zhiqiang Hou
2020-09-16 20:28 ` Rob Herring
2020-09-18 11:02 ` Z.q. Hou
2020-09-18 11:14 ` Michael Walle
2020-09-21 14:48 ` Z.q. Hou
2020-09-18 12:47 ` Bjorn Helgaas [this message]
2020-09-21 16:31 ` Z.q. Hou
2020-09-18 15:27 ` Rob Herring
2020-09-24 4:24 ` Z.q. Hou
2020-09-28 9:39 ` Lorenzo Pieralisi
2020-09-29 4:05 ` Z.q. Hou
2020-09-29 15:24 ` Gustavo Pimentel
2020-09-29 17:11 ` Rob Herring
2020-09-30 13:22 ` Kishon Vijay Abraham I
2020-09-30 15:01 ` Rob Herring
2020-10-01 13:32 ` Kishon Vijay Abraham I
2020-10-01 16:46 ` Michael Walle
2020-10-02 9:29 ` Naresh Kamboju
2020-10-08 14:46 ` Naresh Kamboju
2020-10-08 15:12 ` Rob Herring
2020-10-08 16:51 ` Naresh Kamboju
2020-10-08 15:08 ` Lorenzo Pieralisi
2020-10-12 16:31 ` Kishon Vijay Abraham I
2020-10-12 4:41 ` Z.q. Hou
2020-10-19 16:13 ` Lorenzo Pieralisi
2020-10-20 8:07 ` Kishon Vijay Abraham I
2020-10-12 4:22 ` Z.q. Hou
2020-10-20 9:48 ` Lorenzo Pieralisi
2020-10-13 9:15 ` Lorenzo Pieralisi
2020-10-14 11:13 ` Lorenzo Pieralisi
2020-10-14 12:37 ` Rob Herring
2020-10-15 22:47 ` Bjorn Helgaas
2020-10-16 11:59 ` Lorenzo Pieralisi
2020-10-19 5:24 ` Z.q. Hou
2020-10-19 5:41 ` Kishon Vijay Abraham I
2020-10-20 2:13 ` Z.q. Hou
2020-10-20 9:12 ` Lorenzo Pieralisi
2020-10-20 9:55 ` Lorenzo Pieralisi
2020-10-21 8:47 ` Z.q. Hou
2020-10-22 6:20 ` Richard Zhu
2020-10-19 16:26 ` Lorenzo Pieralisi
2020-10-20 10:19 ` Lorenzo Pieralisi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200918124710.GA1800067@bjorn-Precision-5520 \
--to=helgaas@kernel.org \
--cc=ardb@kernel.org \
--cc=bhelgaas@google.com \
--cc=gustavo.pimentel@synopsys.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lorenzo.pieralisi@arm.com \
--cc=michael@walle.cc \
--cc=robh@kernel.org \
--cc=zhiqiang.hou@nxp.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).