linux-kernel - [PATCH v1 12/13] PCI: Preserve MPS and MRRS when applying

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Message-ID: <20140912180409.1630.66534.stgit@bhelgaas-glaptop2.roam.corp.google.com>
Date:	Fri, 12 Sep 2014 12:04:09 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	linux-pci@...r.kernel.org
Cc:	Rajat Jain <rajatxjain@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH v1 12/13] PCI: Preserve MPS and MRRS when applying _HPX
 settings

Linux manages MPS and MRRS settings to keep them consistent across the PCIe
fabric.  BIOS doesn't participate in Linux scheme, so ignore that part of
any _HPX settings it supplies.

Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/pci/probe.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1ff2105ba401..cb411fbb6435 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1301,6 +1301,16 @@ static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp)
 		return;
 	}
 
+	/*
+	 * Don't allow _HPX to change MPS or MRRS settings.  We manage
+	 * those to make sure they're consistent with the rest of the
+	 * platform.
+	 */
+	hpp->pci_exp_devctl_and |= PCI_EXP_DEVCTL_PAYLOAD |
+				    PCI_EXP_DEVCTL_READRQ;
+	hpp->pci_exp_devctl_or &= ~(PCI_EXP_DEVCTL_PAYLOAD |
+				    PCI_EXP_DEVCTL_READRQ);
+
 	/* Initialize Device Control Register */
 	pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
 			~hpp->pci_exp_devctl_and, hpp->pci_exp_devctl_or);

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