linux-kernel - [PATCH] pci-e: ignore unknown capability and continue searching

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Message-Id: <1222748945.3887.7.camel@ymzhang>
Date:	Tue, 30 Sep 2008 12:29:05 +0800
From:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
To:	Greg KH <greg@...ah.com>, jbarnes@...tuousgeek.org
Cc:	LKML <linux-kernel@...r.kernel.org>, czernecki@...il.com
Subject: [PATCH] pci-e: ignore unknown capability and continue searching

Subject: pci-e: ignore unknown capability and continue searching
From: "Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>


Tomasz reported AER driver couldn't work on his machine. With the output
of "lcpsi -vvv", I found the root port's extended capabilities are
         Capabilities: [100] Unknown (11)
         Capabilities: [150] Advanced Error Reporting
         Capabilities: [190] Unknown (13)
Such Unknown capability is not expected. During pci-e initialization,function
get_port_device_capability just returns if it hits an unknown capability when
searching the AER capability.

I worked out a patch against 2.6.27-rc7. When hitting an unkown capability,
function get_port_device_capability continues the searching.

Tomasz tested it and the patch does work well.

Signed-off-by Zhang Yanmin <yanmin.zhang@...ux.intel.com>
Reported-by Tomasz Czernecki <czernecki@...il.com>

---

--- linux-2.6.27-rc7/drivers/pci/pcie/portdrv_core.c	2008-09-27 09:35:32.000000000 +0800
+++ linux-2.6.27-rc7_aer/drivers/pci/pcie/portdrv_core.c	2008-09-27 10:10:39.000000000 +0800
@@ -195,23 +195,25 @@ static int get_port_device_capability(st
 	/* PME Capable - root port capability */
 	if (((reg16 >> 4) & PORT_TYPE_MASK) == PCIE_RC_PORT)
 		services |= PCIE_PORT_SERVICE_PME;
-	
+
 	pos = PCI_CFG_SPACE_SIZE;
 	while (pos) {
-		pci_read_config_dword(dev, pos, &reg32);
-		switch (reg32 & 0xffff) {
+		if (pci_read_config_dword(dev, pos, &reg32))
+			break;
+
+		/* some broken boards return ~0 */
+		if (reg32 == 0xffffffff)
+			break;
+
+		switch (PCI_EXT_CAP_ID(reg32)) {
 		case PCI_EXT_CAP_ID_ERR:
 			services |= PCIE_PORT_SERVICE_AER;
-			pos = reg32 >> 20;
 			break;
 		case PCI_EXT_CAP_ID_VC:
 			services |= PCIE_PORT_SERVICE_VC;
-			pos = reg32 >> 20;
-			break;
-		default:
-			pos = 0;
 			break;
 		}
+		pos = PCI_EXT_CAP_NEXT(reg32);
 	}
 
 	return services;



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