linux-kernel - [PATCH -v2 16/16] PCI: latency timer doesn't apply to PCIe

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Message-ID: <20111028214920.20088.85205.stgit@amt.stowe>
Date:	Fri, 28 Oct 2011 15:49:20 -0600
From:	Myron Stowe <myron.stowe@...hat.com>
To:	jbarnes@...tuousgeek.org
Cc:	linux-pci@...r.kernel.org, linux@....linux.org.uk,
	vapier@...too.org, dhowells@...hat.com, ysato@...rs.sourceforge.jp,
	tony.luck@...el.com, fenghua.yu@...el.com, monstr@...str.eu,
	ralf@...ux-mips.org, benh@...nel.crashing.org, paulus@...ba.org,
	lethal@...ux-sh.org, davem@...emloft.net, cmetcalf@...era.com,
	gxt@...c.pku.edu.cn, tglx@...utronix.de, mingo@...hat.com,
	chris@...kel.net, linux-kernel@...r.kernel.org
Subject: [PATCH -v2 16/16] PCI: latency timer doesn't apply to PCIe

From: Myron Stowe <mstowe@...hat.com>

The latency timer is read-only and hardwired to zero for all PCIe
devices, both Type 0 and Type 1, so don't bother trying to update it
and cluttering the dmesg log with meaningless "setting latency timer
to 64" messages.

Signed-off-by: Myron Stowe <myron.stowe@...hat.com>
---

 drivers/pci/pci.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index a50e643..a20c01a 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2607,6 +2607,10 @@ void __weak pcibios_set_master(struct pci_dev *dev)
 {
 	u8 lat;
 
+	/* The latency timer doesn't apply to PCIe (either Type 0 or Type 1) */
+	if (pci_is_pcie(dev))
+		return;
+
 	pci_read_config_byte(dev, PCI_LATENCY_TIMER, &lat);
 	if (lat < 16)
 		lat = (64 <= pcibios_max_latency) ? 64 : pcibios_max_latency;

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