From: Bjorn Helgaas <helgaas@kernel.org>
To: Marek Vasut <marek.vasut@gmail.com>
Cc: linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Wolfram Sang <wsa@the-dreams.de>,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH V4] PCI: rcar: Add L1 link state fix into data abort hook
Date: Mon, 14 Dec 2020 14:38:05 -0600 [thread overview]
Message-ID: <20201214203805.GA250639@bjorn-Precision-5520> (raw)
In-Reply-To: <a65139b9-3b06-0562-7b6e-9a438aecff66@gmail.com>
On Tue, Dec 08, 2020 at 07:05:09PM +0100, Marek Vasut wrote:
> On 12/8/20 5:40 PM, Bjorn Helgaas wrote:
> > Does this problem occur in both these cases?
> >
> > 1) When ASPM enters L1, and
> >
> > 2) When software writes PCI_PM_CTRL to put the device in D3hot?
> >
> > IIUC both cases require the link to go to L1. I guess the same
> > software workaround applies to both cases?
>
> Yes
If ASPM puts the Link in L1 and the device needs to DMA, how does the
Link get back to L0? Do we use the same data abort hook? If getting
back to L0 requires help from software, it seems like that would
invalidate the L1 exit latency advertised by the devices. Wouldn't
that mean we couldn't safely enable L1 at all unless the endpoint
could tolerate unlimited exit latency?
Bjorn
next prev parent reply other threads:[~2020-12-14 20:39 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-16 12:04 [PATCH V4] PCI: rcar: Add L1 link state fix into data abort hook marek.vasut
2020-10-17 14:03 ` Geert Uytterhoeven
2020-11-19 17:35 ` Lorenzo Pieralisi
2020-11-29 13:05 ` Marek Vasut
2020-12-08 10:18 ` Lorenzo Pieralisi
2020-12-08 17:45 ` Marek Vasut
2020-12-08 17:52 ` Geert Uytterhoeven
2020-12-08 16:40 ` Bjorn Helgaas
2020-12-08 18:05 ` Marek Vasut
2020-12-08 18:46 ` Bjorn Helgaas
2020-12-10 12:12 ` Lorenzo Pieralisi
2020-12-12 19:12 ` Marek Vasut
2020-12-14 17:13 ` Lorenzo Pieralisi
2020-12-16 17:52 ` Marek Vasut
2020-12-12 19:10 ` Marek Vasut
2020-12-14 20:38 ` Bjorn Helgaas [this message]
2020-12-16 17:56 ` Marek Vasut
2020-12-16 18:20 ` 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=20201214203805.GA250639@bjorn-Precision-5520 \
--to=helgaas@kernel.org \
--cc=bhelgaas@google.com \
--cc=geert+renesas@glider.be \
--cc=linux-pci@vger.kernel.org \
--cc=linux-renesas-soc@vger.kernel.org \
--cc=lorenzo.pieralisi@arm.com \
--cc=marek.vasut@gmail.com \
--cc=wsa@the-dreams.de \
--cc=yoshihiro.shimoda.uh@renesas.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).