PCI: complain about devices that seem to be broken

If we can tell that a device isn't working correctly, we should tell
the user to make debugging easier.  Otherwise, it can take a lot of
work to determine whether the problem is in the driver, PCMCIA, PCI,
hardware, etc., as in http://bugzilla.kernel.org/show_bug.cgi?id=12006

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/probe.c

@@ -174,14 +174,19 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 	pci_read_config_dword(dev, pos, &sz);
 	pci_write_config_dword(dev, pos, l);
 
+	if (!sz)
+		goto fail;	/* BAR not implemented */
+
 	/*
 	 * All bits set in sz means the device isn't working properly.
-	 * If the BAR isn't implemented, all bits must be 0.  If it's a
-	 * memory BAR or a ROM, bit 0 must be clear; if it's an io BAR, bit
-	 * 1 must be clear.
+	 * If it's a memory BAR or a ROM, bit 0 must be clear; if it's
+	 * an io BAR, bit 1 must be clear.
 	 */
-	if (!sz || sz == 0xffffffff)
+	if (sz == 0xffffffff) {
+		dev_err(&dev->dev, "reg %x: invalid size %#x; broken device?\n",
+			pos, sz);
 		goto fail;
+	}
 
 	/*
 	 * I don't know how l can have all bits set.  Copied from old code.
@@ -244,13 +249,17 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 				   pos, res);
 		}
 	} else {
-		sz = pci_size(l, sz, mask);
+		u32 size = pci_size(l, sz, mask);
 
-		if (!sz)
+		if (!size) {
+			dev_err(&dev->dev, "reg %x: invalid size "
+			        "(l %#x sz %#x mask %#x); broken device?",
+				pos, l, sz, mask);
 			goto fail;
+		}
 
 		res->start = l;
-		res->end = l + sz;
+		res->end = l + size;
 
 		dev_printk(KERN_DEBUG, &dev->dev, "reg %x: %pR\n", pos, res);
 	}