iwlwifi: delay firmware loading from pci_probe to network interface open
This patch moves the firmware loading (read firmware from disk and load it into the device SRAM) from pci_probe time to the first network interface open time. There are two reasons for doing this: 1. To support kernel buildin iwlwifi drivers. Because kernel initializes network devices subsystem before hard disk and SATA subsystem, it is impossible to get the firmware image from hard disk in the PCI probe handler. Thus delaying the firmware loading into the network interface open time is the way to go. Note, we only read the firmware image from hard disk the first time the interface is open. After this is succeeded, we cache the firmware image into the host memory. This is a performance gain when user open and close the interface multiple times and is necessary for device suspend and resume. 2. For better power saving. When the iwlwifi modules are loaded (or buildin the kernel) but the wireless network interface is not being used, it is a good practice the wireless device consumes as less power as possible. Unloading the firmware from the wireless device and unregister the driver's interrupt handler in the network interface close handler provides users a way to achieve this. User space network configuration tools (i.e NetworkManager) can also contribute here when it detects a wired cable is connected and close the wireless interface automatically. This patch also includes the pci_save/restore_state() fixed by Ian Schram upon the first version. Signed-off-by: Zhu Yi <yi.zhu@intel.com> Signed-off-by: Ian Schram <ischram@telenet.be> Signed-off-by: John W. Linville <linville@tuxdriver.com>
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