PCI: make pci_set_mwi a dummy for PCIe devices
PATCH 1/1 PCI: make pci_set_mwi a dummy for PCIe devices
Memory-Write-Invalidate isn't applicable for PCIe devices, therefore make the MWI functions a dummy and don't even write to the (dummy) PCI config space registers.
--- drivers/pci/pci.c | 6 ++++++ 1 file changed, 6 insertions(+)
drivers/pci/pci.c +6 -0
@@ -4137,6 +4137,9 @@ int pci_set_mwi(struct pci_dev *dev)int rc;u16 cmd; +if (pci_is_pcie (dev)) +return 0 ; + rc =pci_set_cacheline_size (dev);if (rc)return rc;
@@ -4203,6 +4206,9 @@ void pci_clear_mwi(struct pci_dev *dev)#ifndef PCI_DISABLE_MWI u16 cmd; +if (pci_is_pcie (dev)) +return ; +pci_read_config_word (dev,PCI_COMMAND , &cmd);if (cmd &PCI_COMMAND_INVALIDATE ) { cmd &= ~PCI_COMMAND_INVALIDATE ;
Signature · 1 line
2.19.1
Quoted 14 lines · Heiner Kallweit
Memory-Write-Invalidate isn't applicable for PCIe devices, therefore make the MWI functions a dummy and don't even write to the (dummy) PCI config space registers.
Signed-off-by Heiner Kallweit <[email protected]>--- drivers/pci/pci.c | 6 ++++++ 1 file changed, 6 insertions(+)drivers/pci/pci.c +0
-0
drivers/pci/pci.c int pci_set_mwi(struct pci_dev *dev) · line 4141
Quoted 5 lines
drivers/pci/pci.c +2
-0@@ -4137,6 +4137,9 @@ int pci_set_mwi(struct pci_dev *dev)int rc;u16 cmd; +if (pci_is_pcie (dev)) +return 0 ;
I don't think this works quite right for the case of a PCIe-to-PCI/PCI-X bridge. That is a PCIe device (it has a PCIe Capability, and pci_is_pcie() should return true), but the MWI bit is writable and meaningful (it controls whether the bridge can convert a PCIe Memory Write into a PCI Memory Write and Invalidate), so I don't think it would be correct to just skip this.
I'm looking at the "PCI EXPRESS TO PCI/PCI-X BRIDGE" spec, r1.0, sec 5.1.1.1.
Quoted 16 lines
drivers/pci/pci.c +3
-0rc =pci_set_cacheline_size (dev);if (rc)return rc;@@ -4203,6 +4206,9 @@ void pci_clear_mwi(struct pci_dev *dev)#ifndef PCI_DISABLE_MWI u16 cmd; +if (pci_is_pcie (dev)) +return ; +pci_read_config_word (dev,PCI_COMMAND , &cmd);if (cmd &PCI_COMMAND_INVALIDATE ) { cmd &= ~PCI_COMMAND_INVALIDATE ;Signature · 1 line
2.19.1