PCI_COMMAND_BACKTOBACK_ENABLE
csr |= PCI_COMMAND_BACKTOBACK_ENABLE;
v | PCI_COMMAND_MASTER_ENABLE | PCI_COMMAND_BACKTOBACK_ENABLE);
csr |= PCI_COMMAND_MASTER_ENABLE | PCI_COMMAND_BACKTOBACK_ENABLE;
PCI_COMMAND_BACKTOBACK_ENABLE);
csr &= ~(PCI_COMMAND_MASTER_ENABLE | PCI_COMMAND_BACKTOBACK_ENABLE);
PCI_COMMAND_BACKTOBACK_ENABLE);
cmd |= PCI_COMMAND_BACKTOBACK_ENABLE;