Linux-PCI Archive on lore.kernel.org
 help / color / Atom feed
From: Kai-Heng Feng <kai.heng.feng@canonical.com>
To: bhelgaas@google.com
Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Keith Busch <keith.busch@intel.com>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Chris Packham <chris.packham@alliedtelesis.co.nz>,
	Yicong Yang <yangyicong@hisilicon.com>,
	Krzysztof Wilczynski <kw@linux.com>,
	linux-pci@vger.kernel.org (open list:PCI SUBSYSTEM),
	linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v3] PCI/ASPM: Enable ASPM for bridge-to-bridge link
Date: Wed,  6 May 2020 01:34:21 +0800
Message-ID: <20200505173423.26968-1-kai.heng.feng@canonical.com> (raw)
In-Reply-To: <20200505122801.12903-1-kai.heng.feng@canonical.com>

The TI PCIe-to-PCI bridge prevents the Intel SoC from entering power
state deeper than PC3 due to disabled ASPM, consumes lots of unnecessary
power. On Windows ASPM L1 is enabled on the device and its upstream
bridge, so it can make the Intel SoC reach PC8 or PC10 to save lots of
power.

In short, ASPM always gets disabled on bridge-to-bridge link.

The special case was part of first ASPM introduction patch, commit
7d715a6c1ae5 ("PCI: add PCI Express ASPM support"). However, it didn't
explain why ASPM needs to be disabled in special bridge-to-bridge case.

Let's remove the the special case, as PCIe spec already envisioned ASPM
on bridge-to-bridge link.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=207571
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v3:
 - Remove the special case completely.

v2: 
 - Enable ASPM on root complex <-> bridge <-> bridge, instead of using
   quirk.
 drivers/pci/pcie/aspm.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 2378ed692534..b17e5ffd31b1 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -628,16 +628,6 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
 
 	/* Setup initial capable state. Will be updated later */
 	link->aspm_capable = link->aspm_support;
-	/*
-	 * If the downstream component has pci bridge function, don't
-	 * do ASPM for now.
-	 */
-	list_for_each_entry(child, &linkbus->devices, bus_list) {
-		if (pci_pcie_type(child) == PCI_EXP_TYPE_PCI_BRIDGE) {
-			link->aspm_disable = ASPM_STATE_ALL;
-			break;
-		}
-	}
 
 	/* Get and check endpoint acceptable latencies */
 	list_for_each_entry(child, &linkbus->devices, bus_list) {
-- 
2.17.1


  parent reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-04  7:02 [PATCH] PCI: Enable ASPM L1 on TI PCIe-to-PCI bridge Kai-Heng Feng
2020-05-04 14:15 ` Bjorn Helgaas
2020-05-05 12:27 ` [PATCH v2] PCI/ASPM: Enable ASPM for root complex <-> bridge <-> bridge case Kai-Heng Feng
2020-05-05 13:38   ` Bjorn Helgaas
2020-05-05 14:00     ` Kai-Heng Feng
2020-05-05 15:45       ` Bjorn Helgaas
2020-05-05 17:34   ` Kai-Heng Feng [this message]
2020-05-06  6:14     ` [PATCH v3] PCI/ASPM: Enable ASPM for bridge-to-bridge link Mika Westerberg
2020-05-06 21:29       ` Bjorn Helgaas
2020-05-07 11:50         ` Mika Westerberg
2020-05-07 22:19     ` 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=20200505173423.26968-1-kai.heng.feng@canonical.com \
    --to=kai.heng.feng@canonical.com \
    --cc=bhelgaas@google.com \
    --cc=chris.packham@alliedtelesis.co.nz \
    --cc=hkallweit1@gmail.com \
    --cc=keith.busch@intel.com \
    --cc=kw@linux.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=mika.westerberg@linux.intel.com \
    --cc=rafael.j.wysocki@intel.com \
    --cc=yangyicong@hisilicon.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

Linux-PCI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pci/0 linux-pci/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pci linux-pci/ https://lore.kernel.org/linux-pci \
		linux-pci@vger.kernel.org
	public-inbox-index linux-pci

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pci


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git