linux-kernel - [Bug #11550] pnp: Huge number of "io resource overlap" messages

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Date:	Wed, 4 Mar 2009 21:17:15 +0100
From:	Frans Pop <elendil@...net.nl>
To:	Bjorn Helgaas <bjorn.helgaas@...com>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Matthew Wilcox <matthew@....cx>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Rene Herman <rene.herman@...access.nl>
Subject: [Bug #11550] pnp: Huge number of "io resource overlap" messages

On Friday 26 September 2008, Bjorn Helgaas wrote:
> http://bugzilla.kernel.org/show_bug.cgi?id=11550

Sorry for having to revive this old thread. In November 2008 I reported
that this issue had been solved for me as a result of 1f98757776ea, but I
now find that was due to faulty testing. (I suspect that changing the BIOS
setting that affects this issue on my Toshiba laptop only takes effect
after a cold boot, not a normal reboot.)

The problem was that with the BIOS setting for "Device config" set to
"Setup by OS", I get 78 messages like:
    pnp 00:08: io resource (0x2e-0x2f) overlaps 0000:00:1f.5 BAR 0 (0x0-0xff), disabling
    pnp 00:08: io resource (0x2e-0x2f) overlaps 0000:00:1f.6 BAR 0 (0x0-0xff), disabling

If the BIOS setting is set to "All Devices", the problem does not occur.

The origin of these messages was bisected to:
commit aee3ad815dd291a7193ab01da0f1a30c84d00061
Author: Bjorn Helgaas <bjorn.helgaas@...com>
Date:   Fri Jun 27 16:56:57 2008 -0600
    PNP: replace pnp_resource_table with dynamically allocated resources

Last analysis from Bjorn was:
> The problem seems to be that Frans has some PCI devices that are not
> configured by the BIOS, and their BARs contain zero.  A PNP quirk
> checks for overlaps of PCI devices and PNP devices, and those zero-
> valued BARs of course conflict with the PNP motherboard devices that
> describe legacy hardware.
>
> Here's another approach based on section 3.5 of the PCI Firmware spec.
> It says:
>
>   Since not all devices may be configured prior to the operating
>   system handoff, the operating system needs to know whether a
>   specific BAR register has been configured by firmware. The operating
>   system makes the determination by checking the I/O Enable, and
>   Memory Enable bits in the device's command register, and Expansion
>   ROM BAR enable bits. If the enable bit is set, then the corresponding
>   resource register has been configured.
>
> So instead of checking whether the BAR contains zero, the patch below
> checks the I/O, Mem, and ROM BAR enable bits to determine whether a
> BAR is enabled.

Below the then proposed patch from Bjorn, rediffed against 2.6.29-rc7.
I've verified that the patch still solves the issue for me. Attached
dmesg output for 2.6.29-rc7 without and with the patch.

Bjorn, could you please consider this patch for inclusion again?

Original thread: http://marc.info/?l=linux-kernel&m=122095745403793&w=4

TIA and sorry for the confusion,
FJP


diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 32e8d88..e63f800 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -26,6 +26,28 @@
 #include "pci.h"
 
 
+int pci_resource_enabled(struct pci_dev *dev, int bar)
+{
+	u16 command = 0;
+	u32 addr = 0;
+
+	pci_read_config_word(dev, PCI_COMMAND, &command);
+
+	if (pci_resource_flags(dev, bar) & IORESOURCE_IO)
+		return command & PCI_COMMAND_IO;
+
+	if (command & PCI_COMMAND_MEMORY) {
+		if (bar == PCI_ROM_RESOURCE) {
+			pci_read_config_dword(dev, dev->rom_base_reg, &addr);
+			return addr & PCI_ROM_ADDRESS_ENABLE;
+		}
+
+		return 1;
+	}
+
+	return 0;
+}
+
 void pci_update_resource(struct pci_dev *dev, int resno)
 {
 	struct pci_bus_region region;
diff --git a/drivers/pnp/quirks.c b/drivers/pnp/quirks.c
index 8473fe5..1f37988 100644
--- a/drivers/pnp/quirks.c
+++ b/drivers/pnp/quirks.c
@@ -247,6 +247,9 @@ static void quirk_system_pci_resources(struct pnp_dev *dev)
 		for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
 			unsigned long type;
 
+			if (!pci_resource_enabled(pdev, i))
+				continue;
+
 			type = pci_resource_flags(pdev, i) &
 					(IORESOURCE_IO | IORESOURCE_MEM);
 			if (!type || pci_resource_len(pdev, i) == 0)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c927ae9..9848ac2 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -870,6 +870,8 @@ static inline int pci_proc_domain(struct pci_bus *bus)
 }
 #endif /* CONFIG_PCI_DOMAINS */
 
+extern int pci_resource_enabled(struct pci_dev *dev, int bar);
+
 #else /* CONFIG_PCI is not enabled */
 
 /*
@@ -1050,6 +1052,9 @@ static inline struct pci_dev *pci_get_bus_and_slot(unsigned int bus,
 						unsigned int devfn)
 { return NULL; }
 
+static inline int pci_resource_enabled(struct pci_dev *dev, int bar)
+{ return 0; }
+
 #endif /* CONFIG_PCI */
 
 /* Include architecture-dependent settings and functions */


View attachment "2.6.29-rc7" of type "text/plain" (30943 bytes)

View attachment "2.6.29-rc7.patched" of type "text/plain" (24301 bytes)