From: joelopez333 <jlo...@gmail.com>
REF:https://edk2.groups.io/g/devel/topic/102310377#110456
- Add a read after the final PCI Configuration space write
in RootBridgeIoPciAccess.
- When configuration space is strongly ordered, this ensures
that program execution cannot continue until the completion
is received for the previous Cfg-Write, which may have side-effects.
Cc: Leif Lindholm <quic_llind...@quicinc.com>
Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>
Cc: Sami Mujawar <sami.muja...@arm.com>
Cc: Jian J Wang <jian.j.w...@intel.com>
Cc: Liming Gao <gaolim...@byosoft.com.cn>
Cc: Hao A Wu <hao.a...@intel.com>
Cc: Ray Ni <ray...@intel.com>
Cc: Pedro Falcato <pedro.falc...@gmail.com>
Cc: Michael Brown <mc...@ipxe.org>
Signed-off-by: Joe Lopez <jlo...@gmail.com>
---
MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
index 157a0ada80..4bc774b574 100644
--- a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
+++ b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
@@ -1238,6 +1238,13 @@ RootBridgeIoPciAccess (
}
}
+ //
+ // Perform readback after write to confirm completion was received for the
last write
+ //
+ if (!Read) {
+ PciSegmentRead8 (Address - InStride);
+ }
+
return EFI_SUCCESS;
}
--
2.25.1
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