linux-kernel - [PATCH] PCI: Apply _HPX settings only to relevant devices

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Date:   Thu, 12 Jan 2017 14:32:04 -0600
From:   Bjorn Helgaas <bhelgaas@...gle.com>
To:     linux-pci@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] PCI: Apply _HPX settings only to relevant devices

Previously we didn't check the type of device before trying to apply Type 1
(PCI-X) or Type 2 (PCIe) Setting Records from _HPX.

We don't support PCI-X Setting Records, so this was harmless, but the
warning was useless.

We do support PCIe Setting Records, and we didn't check whether a device
was PCIe before applying settings.  I don't think anything bad happened on
non-PCIe devices because pcie_capability_clear_and_set_word(),
pcie_cap_has_lnkctl(), etc., would fail before doing any harm.  But it's
ugly to depend on those internals.

Check the device type before attempting to apply Type 1 and Type 2 Setting
Records (Type 0 records are applicable to PCI, PCI-X, and PCIe devices).

A side benefit is that this prevents useless "not supported" warnings when
a BIOS supplies a Type 1 (PCI-X) Setting Record and we try to apply it to
every single device:

  pci 0000:00:00.0: PCI-X settings not supported

After this patch, we'll get the warning only when a BIOS supplies a Type 1
record and we have a PCI-X device to which it should be applied.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=187731
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/pci/probe.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e164b5c9f0f0..aca5b2466adb 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1554,8 +1554,16 @@ static void program_hpp_type0(struct pci_dev *dev, struct hpp_type0 *hpp)

 static void program_hpp_type1(struct pci_dev *dev, struct hpp_type1 *hpp)
 {
-	if (hpp)
-		dev_warn(&dev->dev, "PCI-X settings not supported\n");
+	int pos;
+
+	if (!hpp)
+		return;
+
+	pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
+	if (!pos)
+		return;
+
+	dev_warn(&dev->dev, "PCI-X settings not supported\n");
 }

 static bool pcie_root_rcb_set(struct pci_dev *dev)
@@ -1581,6 +1589,9 @@ static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp)
 	if (!hpp)
 		return;

+	if (!pci_is_pcie(dev))
+		return;
+
 	if (hpp->revision > 1) {
 		dev_warn(&dev->dev, "PCIe settings rev %d not supported\n",
 			 hpp->revision);