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MdeModulePkg: exit pci function loops early if device is not multi-function 

When looping through all PCI functions, code should not look for functions
1-7 if function 0 is not present or if function 0 indicates the device is
not multifunction.  Prior to this fix the code would use stale data in a
buffer to determine if a device is multifunction even if function 0 is not
present.  This fixes a code bug and provides very small performance
improvements.

PCI 2.3 Specification states: They [multifunction devices] are also
required to always implement function 0 in the device. Implementing other
functions is optional and may be assigned in any order.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Joseph Shifflett <joseph.shifflett@hpe.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18574 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Joseph Shifflett 2015-10-06 20:55:31 +00:00 committed by lersek
parent c5a693cea6
commit 25a2664625
3 changed files with 32 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumerator.c
View File

@ -2,6 +2,7 @@
PCI eunmeration implementation on entire PCI bus system for PCI Bus module.
Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
@ -407,6 +408,13 @@ PciAssignBusNumber (
Func
);
if (EFI_ERROR (Status) && Func == 0) {
//
// go to next device if there is no Function 0
//
break;
}
if (!EFI_ERROR (Status) &&
(IS_PCI_BRIDGE (&Pci) || IS_CARDBUS_BRIDGE (&Pci))) {

16
MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
View File

@ -2,6 +2,7 @@
PCI emumeration support functions implementation for PCI Bus module.
Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
@ -119,6 +120,14 @@ PciPciDeviceInfoCollector (
(UINT8) Device,
(UINT8) Func
);
if (EFI_ERROR (Status) && Func == 0) {
//
// go to next device if there is no Function 0
//
break;
}
if (!EFI_ERROR (Status)) {
//
@ -2597,6 +2606,13 @@ ResetAllPpbBusNumber (
Func
);
if (EFI_ERROR (Status) && Func == 0) {
//
// go to next device if there is no Function 0
//
break;
}
if (!EFI_ERROR (Status) && (IS_PCI_BRIDGE (&Pci))) {
Register = 0;

8
MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c
View File

@ -2,6 +2,7 @@
Internal library implementation for PCI Bus module.
Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
@ -1022,6 +1023,13 @@ PciScanBus (
Func
);
if (EFI_ERROR (Status) && Func == 0) {
//
// go to next device if there is no Function 0
//
break;
}
if (EFI_ERROR (Status)) {
continue;
}