pci_enable_device()與pci_enable_device_mem()區別

pci_enable_device()與pci_enable_device_mem()區別

1. pci_enable_device()源碼

/**
 * pci_enable_device - Initialize device before it's used by a driver.
 * @dev: PCI device to be initialized
 *
 *  Initialize device before it's used by a driver. Ask low-level code
 *  to enable I/O and memory. Wake up the device if it was suspended.
 *  Beware, this function can fail.
 *
 *  Note we don't actually enable the device many times if we call
 *  this function repeatedly (we just increment the count).
 */
int pci_enable_device(struct pci_dev *dev)
{
	return pci_enable_device_flags(dev, IORESOURCE_MEM | IORESOURCE_IO);
}

2. pci_enable_device_mem()源碼

/**
 * pci_enable_device_mem - Initialize a device for use with Memory space
 * @dev: PCI device to be initialized
 *
 *  Initialize device before it's used by a driver. Ask low-level code
 *  to enable Memory resources. Wake up the device if it was suspended.
 *  Beware, this function can fail.
 */
int pci_enable_device_mem(struct pci_dev *dev)
{
	return pci_enable_device_flags(dev, IORESOURCE_MEM);
}

3. 區別

PCI/PCIE的BAR有兩種類型，memory和IO。pci_enable_device_mem()只初始化memory類型的BAR，pci_enable_device()同時初始化memory和IO類型的BAR。如果要驅動的PCI/PCIE設備包含IO空間，那麼必須使用pci_enable_device()。