From: Bjorn Helgaas <helgaas@kernel.org>
To: Nathan Chancellor <nathan@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux PCI <linux-pci@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Anders Roxell <anders.roxell@linaro.org>
Subject: Re: [PATCH v3 4/9] PCI/PM: Rework changing power states of PCI devices
Date: Wed, 4 May 2022 11:54:09 -0500 [thread overview]
Message-ID: <20220504165409.GA453565@bhelgaas> (raw)
In-Reply-To: <YnFtjzGYwe28tVAA@dev-arch.thelio-3990X>
[+cc Anders]
On Tue, May 03, 2022 at 10:59:43AM -0700, Nathan Chancellor wrote:
> On Thu, Apr 14, 2022 at 03:11:21PM +0200, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > There are some issues related to changing power states of PCI
> > devices, mostly related to carrying out unnecessary actions in some
> > places, and the code is generally hard to follow.
> >
> > 1. pci_power_up() has two callers, pci_set_power_state() and
> > pci_pm_default_resume_early(). The latter updates the current
> > power state of the device right after calling pci_power_up()
> > and it restores the entire config space of the device right
> > after that, so pci_power_up() itself need not read the
> > PCI_PM_CTRL register or restore the BARs after programming the
> > device into D0 in that case.
> >
> > 2. It is generally hard to get a clear view of the pci_power_up()
> > code flow, especially in some corner cases, due to all of the
> > involved PCI_PM_CTRL register reads and writes occurring in
> > pci_platform_power_transition() and in pci_raw_set_power_state(),
> > some of which are redundant.
> >
> > 3. The transitions from low-power states to D0 and the other way
> > around are unnecessarily tangled in pci_raw_set_power_state()
> > which causes it to use a redundant local variable and makes it
> > rather hard to follow.
> >
> > To address the above shortcomings, make the following changes:
> >
> > a. Remove the code handling transitions into D0
> > from pci_raw_set_power_state() and rename it as
> > pci_set_low_power_state().
> >
> > b. Add the code handling transitions into D0 directly
> > to pci_power_up() and to a new wrapper function
> > pci_set_full_power_state() calling it internally that is
> > only used in pci_set_power_state().
> >
> > c. Make pci_power_up() avoid redundant PCI_PM_CTRL register reads
> > and make it work in the same way for transitions from any
> > low-power states (transitions from D1 and D2 are handled
> > slightly differently before the change).
> >
> > d. Put the restoration of the BARs and the PCI_PM_CTRL
> > register read confirming the power state change into
> > pci_set_full_power_state() to avoid doing that in
> > pci_pm_default_resume_early() unnecessarily.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
>
> This change as commit 5bffe4c611f5 ("PCI/PM: Rework changing power
> states of PCI devices") causes my AMD-based system to fail to fully
> boot.
I dropped 5bffe4c611f5 and subsequent pci/pm patches temporarily while
this gets worked out.
Bjorn
next prev parent reply other threads:[~2022-05-04 17:03 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-09 13:03 [PATCH v1 0/7] PCI/PM: Improvements related to device transitions into D0 Rafael J. Wysocki
2022-04-09 13:05 ` [PATCH v1 1/7] PCI/PM: Resume subordinate bus in bus type callbacks Rafael J. Wysocki
2022-04-09 13:06 ` [PATCH v1 2/7] PCI/PM: Drop the runtime_d3cold PCI device flag Rafael J. Wysocki
2022-04-09 13:08 ` [PATCH v1 3/7] PCI/PM: Rearrange pci_update_current_state() Rafael J. Wysocki
2022-04-09 13:22 ` [PATCH v1 4/7] PCI/PM: Rework changing power states of PCI devices Rafael J. Wysocki
2022-04-09 13:23 ` [PATCH v1 5/7] PCI/PM: Move pci_set_low_power_state() next to its caller Rafael J. Wysocki
2022-04-09 13:26 ` [PATCH v1 6/7] PCI/PM: Clean up pci_set_low_power_state() Rafael J. Wysocki
2022-04-09 13:28 ` [PATCH v1 7/7] PCI/PM: Rearrange pci_set_power_state() Rafael J. Wysocki
2022-04-11 14:17 ` [PATCH v2 0/9] PCI/PM: Improvements related to device transitions into D0 Rafael J. Wysocki
2022-04-11 14:19 ` [PATCH v2 1/9] PCI/PM: Resume subordinate bus in bus type callbacks Rafael J. Wysocki
2022-04-11 14:20 ` [PATCH v2 2/9] PCI/PM: Drop the runtime_d3cold device flag Rafael J. Wysocki
2022-04-11 14:21 ` [PATCH v2 3/9] PCI/PM: Rearrange pci_update_current_state() Rafael J. Wysocki
2022-04-12 9:42 ` Mika Westerberg
2022-04-12 10:56 ` Rafael J. Wysocki
2022-04-11 14:25 ` [PATCH v2 4/9] PCI/PM: Rework changing power states of PCI devices Rafael J. Wysocki
2022-04-12 10:00 ` Mika Westerberg
2022-04-12 11:31 ` Rafael J. Wysocki
2022-04-12 11:38 ` Mika Westerberg
2022-04-11 14:27 ` [PATCH v2 5/9] PCI/PM: Move pci_set_low_power_state() next to its caller Rafael J. Wysocki
2022-04-11 14:28 ` [PATCH v2 6/9] PCI/PM: Clean up pci_set_low_power_state() Rafael J. Wysocki
2022-04-11 14:30 ` [PATCH v2 7/9] PCI/PM: Rearrange pci_set_power_state() Rafael J. Wysocki
2022-04-11 14:31 ` [PATCH v2 8/9] PCI/PM: Avoid redundant current_state update Rafael J. Wysocki
2022-04-11 14:33 ` [PATCH v2 9/9] PCI/PM: Replace pci_set_power_state() in pci_pm_thaw_noirq() Rafael J. Wysocki
2022-04-11 14:33 ` [PATCH v2 0/9] PCI/PM: Improvements related to device transitions into D0 Rafael J. Wysocki
2022-04-12 10:08 ` Mika Westerberg
2022-04-12 11:34 ` Rafael J. Wysocki
2022-04-14 13:00 ` [PATCH v3 " Rafael J. Wysocki
2022-04-14 13:04 ` [PATCH v3 1/9] PCI/PM: Resume subordinate bus in bus type callbacks Rafael J. Wysocki
2022-04-14 13:04 ` [PATCH v3 2/9] PCI/PM: Drop the runtime_d3cold device flag Rafael J. Wysocki
2022-04-14 13:07 ` [PATCH v3 3/9] PCI/PM: Rearrange pci_update_current_state() Rafael J. Wysocki
2022-04-14 13:11 ` [PATCH v3 4/9] PCI/PM: Rework changing power states of PCI devices Rafael J. Wysocki
2022-05-03 17:59 ` Nathan Chancellor
2022-05-04 12:59 ` Rafael J. Wysocki
2022-05-04 15:54 ` Anders Roxell
2022-05-04 16:36 ` Nathan Chancellor
2022-05-04 18:00 ` Rafael J. Wysocki
2022-05-04 19:35 ` Nathan Chancellor
2022-05-05 11:58 ` Rafael J. Wysocki
2022-05-04 16:54 ` Bjorn Helgaas [this message]
2022-05-04 17:15 ` Rafael J. Wysocki
2022-04-14 13:14 ` [PATCH v3 5/9] PCI/PM: Move pci_set_low_power_state() next to its caller Rafael J. Wysocki
2022-04-14 13:15 ` [PATCH v3 6/9] PCI/PM: Clean up pci_set_low_power_state() Rafael J. Wysocki
2022-04-14 13:17 ` [PATCH v3 7/9] PCI/PM: Rearrange pci_set_power_state() Rafael J. Wysocki
2022-04-14 13:18 ` [PATCH v3 8/9] PCI/PM: Avoid redundant current_state update Rafael J. Wysocki
2022-04-14 13:19 ` [PATCH v3 9/9] PCI/PM: Replace pci_set_power_state() in pci_pm_thaw_noirq() Rafael J. Wysocki
2022-04-20 16:25 ` [PATCH v3 0/9] PCI/PM: Improvements related to device transitions into D0 Bjorn Helgaas
2022-04-20 16:28 ` Rafael J. Wysocki
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=20220504165409.GA453565@bhelgaas \
--to=helgaas@kernel.org \
--cc=anders.roxell@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=mika.westerberg@linux.intel.com \
--cc=nathan@kernel.org \
--cc=rjw@rjwysocki.net \
/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).