From: "Jan Beulich" <JBeulich@suse.com>
To: "Govinda Tatti" <govinda.tatti@oracle.com>
Cc: <roger.pau@citrix.com>, <xen-devel@lists.xenproject.org>,
<boris.ostrovsky@oracle.com>, "Juergen Gross" <jgross@suse.com>,
<linux-kernel@vger.kernel.org>
Subject: Re: [Xen-devel] [PATCH V2] Xen/pciback: Implement PCI slot or bus reset with 'do_flr' SysFS attribute
Date: Thu, 30 Nov 2017 07:46:56 -0700 [thread overview]
Message-ID: <5A2027F00200007800193936@prv-mh.provo.novell.com> (raw)
In-Reply-To: <71644190-6e18-94a4-4da5-e65c041fb45a@oracle.com>
>>> On 30.11.17 at 15:15, <govinda.tatti@oracle.com> wrote:
> On 11/30/2017 2:27 AM, Jan Beulich wrote:
>>>>> On 29.11.17 at 18:38, <govinda.tatti@oracle.com> wrote:
>>>>> In the case of bus or slot reset, our goal is to reset connected PCIe
>>>>> fabric/card/endpoint.
>>>>> The connected card/endpoint can be multi-function device. So, same
>>>>> walk-through and checking
>>>>> is needed irrespective of type of reset being used.
>>>> I don't follow: The scope of other devices/functions possibly
>>>> affected by a reset depends on the type of reset, doesn't it?
>>> For PCIe platforms, both slot and bus reset endup resetting all connected
>>> device/functions on thesecondary bus (behind the root-port or
>>> downstream-port).
>> According to my understanding this contradicts the comment
>> ahead of pci_reset_slot(), which talks of multiple slots per bus.
>> In such a setup, I can't see why resetting on slot would affect
>> other slots on the same bus. At the same time the comment
>> says that the slot reset may resolve to a bus one when there's
>> just a single slot on the bus.
> For legacy PCI/PCI-X, we can have multiple slots per bus but not with
> PCI-Express
> (each link will be on a separate bus).
Is that true even for root complex integrated end points? A
random system's lspci output doesn't seem to agree with what
you say. A typical example would be USB controllers all sitting
on bus 0, but having different slot numbers. You clearly won't
be able to ever bus-reset these, and if you checked all devices
on bus 0 you would then also not be able to slot-reset them.
Jan
next prev parent reply other threads:[~2017-11-30 14:47 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-08 23:06 [PATCH V2] Xen/pciback: Implement PCI slot or bus reset with 'do_flr' SysFS attribute Govinda Tatti
2017-11-09 8:49 ` Jan Beulich
2017-11-29 15:37 ` [Xen-devel] " Govinda Tatti
2017-11-29 15:50 ` Jan Beulich
2017-11-29 17:38 ` Govinda Tatti
2017-11-30 8:27 ` Jan Beulich
2017-11-30 14:15 ` Govinda Tatti
2017-11-30 14:46 ` Jan Beulich [this message]
2017-12-01 16:16 ` Govinda Tatti
2017-12-04 16:16 ` Govinda Tatti
2017-12-04 16:49 ` Jan Beulich
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=5A2027F00200007800193936@prv-mh.provo.novell.com \
--to=jbeulich@suse.com \
--cc=boris.ostrovsky@oracle.com \
--cc=govinda.tatti@oracle.com \
--cc=jgross@suse.com \
--cc=linux-kernel@vger.kernel.org \
--cc=roger.pau@citrix.com \
--cc=xen-devel@lists.xenproject.org \
/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).