On x86, we do early PCI probing to apply some quirks for chipset bugs.
However, in a recent cleanup (7bcbc78dea92fdf0947fa48e248da3c993a5690f) a
change was introduced that causes us to probe all subfunctions of even single
function devices:
commit 7bcbc78dea92fdf0947fa48e248da3c993a5690f
Author: Neil Horman <nhorman@xxxxxxxxxxxxx>
Date: Wed Jan 30 13:31:26 2008 +0100
x86: clean up arch/x86/kernel/early-quirks.c
clean up checkpatch errors. No code changed.
text data bss dec hex filename
705 120 0 825 339 early-quirks.o.before
705 120 0 825 339 early-quirks.o.after
...
+static void check_dev_quirk(int num, int slot, int func)
+{
+ u16 class;
+ u16 vendor;
+ u16 device;
+ u8 type;
+ int i;
+
+ class = read_pci_config_16(num, slot, func, PCI_CLASS_DEVICE);
+
+ if (class == 0xffff)
+ return;
+
+ vendor = read_pci_config_16(num, slot, func, PCI_VENDOR_ID);
+
+ device = read_pci_config_16(num, slot, func, PCI_DEVICE_ID);
+
+ for (i = 0; early_qrk[i].f != NULL; i++) {
+ if (((early_qrk[i].vendor == PCI_ANY_ID) ||
+ (early_qrk[i].vendor == vendor)) &&
+ ((early_qrk[i].device == PCI_ANY_ID) ||
+ (early_qrk[i].device == device)) &&
+ (!((early_qrk[i].class ^ class) &
+ early_qrk[i].class_mask))) {
+ if ((early_qrk[i].flags &
+ QFLAG_DONE) != QFLAG_DONE)
+ early_qrk[i].f(num, slot, func);
+ early_qrk[i].flags |= QFLAG_APPLIED;
+ }
+ }
+
+ type = read_pci_config_byte(num, slot, func,
+ PCI_HEADER_TYPE);
+ if (!(type & 0x80))
+ return;
+}
+
void __init early_quirks(void)
{
int num, slot, func;
@@ -138,45 +178,8 @@ void __init early_quirks(void)
return;
/* Poor man's PCI discovery */
- for (num = 0; num < 32; num++) {
- for (slot = 0; slot < 32; slot++) {
- for (func = 0; func < 8; func++) {
- u16 class;
- u16 vendor;
- u16 device;
- u8 type;
- int i;
-
- class = read_pci_config_16(num,slot,func,
- PCI_CLASS_REVISION);
- if (class == 0xffff)
- break;
-
- vendor = read_pci_config_16(num, slot, func,
- PCI_VENDOR_ID);
-
- device = read_pci_config_16(num, slot, func,
- PCI_DEVICE_ID);
-
- for(i=0;early_qrk[i].f != NULL;i++) {
- if (((early_qrk[i].vendor == PCI_ANY_ID)
- (early_qrk[i].vendor == vendor)) &&
- ((early_qrk[i].device == PCI_ANY_ID)
- (early_qrk[i].device == device)) &&
- (!((early_qrk[i].class ^ class) &
- early_qrk[i].class_mask))) {
- if ((early_qrk[i].flags & QFLAG_
- early_qrk[i].f(num, slot
- early_qrk[i].flags |= QFLAG_APPL
-
- }
- }
-
- type = read_pci_config_byte(num, slot, func,
- PCI_HEADER_TYPE);
- if (!(type & 0x80))
- break;
- }
- }
- }
+ for (num = 0; num < 32; num++)
+ for (slot = 0; slot < 32; slot++)
+ for (func = 0; func < 8; func++)
+ check_dev_quirk(num, slot, func);
}
...
So even though the code size remained the same, this was a pretty clear change
in behavior (note how the old code would break out of the inner loop to the
middle loop while the new code just has a "return" right before the new
function returns anyway.
This patch fixes things up by adding a return code that allows early_quirks to
skip sub-function probing (rather than pulling check_dev_quirk back in, which
would make things messier).
Any thoughts here?
Thanks,
Jesse
diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 9f51e1e..8566fea 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -133,7 +133,18 @@ static struct chipset early_qrk[] __initdata = {
{}
};
-static void __init check_dev_quirk(int num, int slot, int func)
+/**
+ * check_dev_quirk - apply early quirks to a given PCI device
+ * @num: bus number
+ * @slot: slot number
+ * @func: PCI function
+ *
+ * Check the vendor & device ID against the early quirks table.
+ *
+ * If the device is single function, let early_quirks() know so we don't
+ * poke at this device again.
+ */
+static int __init check_dev_quirk(int num, int slot, int func)
{
u16 class;
u16 vendor;
@@ -144,7 +155,7 @@ static void __init check_dev_quirk(int num, int slot, int func)
class = read_pci_config_16(num, slot, func, PCI_CLASS_DEVICE);
if (class == 0xffff)
- return;
+ return -1; /* no class, treat as single function */
vendor = read_pci_config_16(num, slot, func, PCI_VENDOR_ID);
@@ -167,7 +178,9 @@ static void __init check_dev_quirk(int num, int slot, int func)
type = read_pci_config_byte(num, slot, func,
PCI_HEADER_TYPE);
if (!(type & 0x80))
- return;
+ return -1;
+
+ return 0;
}
void __init early_quirks(void)
@@ -180,6 +193,9 @@ void __init early_quirks(void)
/* Poor man's PCI discovery */
for (num = 0; num < 32; num++)
for (slot = 0; slot < 32; slot++)
- for (func = 0; func < 8; func++)
- check_dev_quirk(num, slot, func);
+ for (func = 0; func < 8; func++) {
+ /* Only probe function 0 on single fn devices */
+ if (check_dev_quirk(num, slot, func))
+ break;
+ }
}
--
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