From 46b4606ba23498d3d0e66b53e498eb3d5d592586 Mon Sep 17 00:00:00 2001 From: xueshengfeng Date: Fri, 24 Sep 2021 14:30:45 +0800 Subject: [PATCH] MdeModulePkg/PciBusDxe: Improve the flow of testing support attributes https://bugzilla.tianocore.org/show_bug.cgi?id=3635 Currently, in order to test the supported attributes, the PciTestSupportedAttribute() will set the command register to 0x27 (EFI_PCI_COMMAND_IO_SPACE, EFI_PCI_COMMAND_MEMORY_SPACE, EFI_PCI_COMMAND_BUS_MASTER, EFI_PCI_COMMAND_VGA_PALETTE_SNOOP) firstly, and then read back to check whether these attributes are set successfully in the device. This will cause the other enabled bits (other than EFI_PCI_COMMAND_IO_SPACE,EFI_PCI_COMMAND_MEMORY_SPACE, EFI_PCI_COMMAND_BUS_MASTER,EFI_PCI_COMMAND_VGA_PALETTE_SNOOP) be cleared for a short of time This patch fixes this issue by keeping the origina enabled bits when setting 0x27. Signed-off-by: xueshengfeng Reviewed-by: Ray --- MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c index db1b35f8ef..3a238d4e46 100644 --- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c +++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c @@ -933,6 +933,7 @@ PciTestSupportedAttribute ( ) { EFI_TPL OldTpl; + UINT16 CommandValue; // // Preserve the original value @@ -943,10 +944,12 @@ PciTestSupportedAttribute ( // Raise TPL to high level to disable timer interrupt while the BAR is probed // OldTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL); + CommandValue = *Command | *OldCommand; - PCI_SET_COMMAND_REGISTER (PciIoDevice, *Command); - PCI_READ_COMMAND_REGISTER (PciIoDevice, Command); + PCI_SET_COMMAND_REGISTER (PciIoDevice, CommandValue); + PCI_READ_COMMAND_REGISTER (PciIoDevice, &CommandValue); + *Command = *Command & CommandValue; // // Write back the original value //