mirror of https://github.com/acidanthera/audk.git
IntelSiliconPkg IntelVTdDxe: Optimize when func 0 is not implemented
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1169 PCI spec: They are also required to always implement function 0 in the device. Implementing other functions is optional and may be assigned in any order (i.e., a two-function device must respond to function 0 but can choose any of the other possible function numbers (1-7) for the second function). This patch updates ScanPciBus() to not scan other functions if function 0 is not implemented. Test done: Added debug code below in the second loop of ScanPciBus(), compared the debug logs with and without this patch, many non-0 unimplemented functions are skipped correctly. DEBUG (( DEBUG_INFO, "%a() B%02xD%02xF%02x VendorId: %04x DeviceId: %04x\n", __FUNCTION__, Bus, Device, Function, VendorID, DeviceID )); Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Rangasai V Chaganty <rangasai.v.chaganty@intel.com> Cc: Tomson Chang <tomson.chang@intel.com> Cc: Jenny Huang <jenny.huang@intel.com> Cc: Amy Chan <amy.chan@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Star Zeng <star.zeng@intel.com> Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
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@ -1,6 +1,6 @@
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/** @file
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Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
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Copyright (c) 2017 - 2018, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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@ -247,6 +247,12 @@ ScanPciBus (
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VendorID = PciSegmentRead16 (PCI_SEGMENT_LIB_ADDRESS(Segment, Bus, Device, Function, PCI_VENDOR_ID_OFFSET));
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DeviceID = PciSegmentRead16 (PCI_SEGMENT_LIB_ADDRESS(Segment, Bus, Device, Function, PCI_DEVICE_ID_OFFSET));
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if (VendorID == 0xFFFF && DeviceID == 0xFFFF) {
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if (Function == 0) {
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//
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// If function 0 is not implemented, do not scan other functions.
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//
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break;
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}
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continue;
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}
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