From: Bjorn Helgaas <helgaas@kernel.org>
To: honghui.zhang@mediatek.com
Cc: youlin.pei@mediatek.com, lorenzo.pieralisi@arm.com,
poza@codeaurora.org, fred@fredlawl.com,
linux-pci@vger.kernel.org, rafael.j.wysocki@intel.com,
linux-kernel@vger.kernel.org, jianjun.wang@mediatek.com,
ryder.lee@mediatek.com, linux-mediatek@lists.infradead.org,
matthias.bgg@gmail.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH] PCI/portdrv: Support for subtractive decode bridge
Date: Thu, 7 Feb 2019 13:52:30 -0600 [thread overview]
Message-ID: <20190207195230.GJ7268@google.com> (raw)
In-Reply-To: <20190207151816.GI7268@google.com>
On Thu, Feb 07, 2019 at 09:18:16AM -0600, Bjorn Helgaas wrote:
> On Fri, Dec 14, 2018 at 11:40:29AM +0800, honghui.zhang@mediatek.com wrote:
> > From: Honghui Zhang <honghui.zhang@mediatek.com>
> >
> > The Class Code for subtractive decode PCI-to-PCI bridge is 060401h,
> > change the class_mask values to make portdrv support this type bridge.
>
> I assume you have a Root Port or Switch Port that supports subtractive
> decode? I'm trying to understand how such a device would work.
>
> Out of curiosity, can you show the "lspci -vv" output for the device
> and the downstream devices of interest?
Actually, since subtractive decode has to do with how the bridge
interacts with its *peers*, what would be interesting is the host
bridge window information from ACPI _CRS or DT and the lspci info for
everything under that host bridge.
Assuming we're talking about a Root Port, I guess that would mean
anything inside the host bridge windows but outside the positive
decode windows (the normal PCI-PCI bridge apertures in the Root Ports)
would be claimed by the subtractive decode Root Port?
I guess you would want this because this path ultimately leads to an
ISA or similar bus where you don't know what resources the device
actually consumes?
Bjorn
next prev parent reply other threads:[~2019-02-07 19:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 3:40 [RFC PATCH] PCI/portdrv: Support for subtractive decode bridge honghui.zhang
2019-02-07 15:18 ` Bjorn Helgaas
2019-02-07 19:52 ` Bjorn Helgaas [this message]
2019-02-12 3:12 ` Honghui Zhang
2019-02-12 2:57 ` Honghui Zhang
2019-02-13 19:11 ` Bjorn Helgaas
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=20190207195230.GJ7268@google.com \
--to=helgaas@kernel.org \
--cc=fred@fredlawl.com \
--cc=honghui.zhang@mediatek.com \
--cc=jianjun.wang@mediatek.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=linux-pci@vger.kernel.org \
--cc=lorenzo.pieralisi@arm.com \
--cc=matthias.bgg@gmail.com \
--cc=poza@codeaurora.org \
--cc=rafael.j.wysocki@intel.com \
--cc=ryder.lee@mediatek.com \
--cc=youlin.pei@mediatek.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).