AM18x Wireless Connectivity Suspend Resume Operation

'''  Content is no longer maintained and is being kept for reference only! '''

Mode of Operation
On Suspend state, the wl1271 chip will be held in shutdown mode, where the host disable the WLAN portion by keeping the WLAN_Enable signal OFF, in that mode the wl1271 consumes minimal current consumption.

How to operate the Suspend resume
The suspend resume mode of operation called "Suspend-to-RAM" that allows the system to enter save power by freezing all tasks, asking all drivers to move the devices to a low power state (by disabling the peripheral clock using its LPSC), cutting the clock to external RAM and finally moving the SoC to DeepSleep mode. in order enter suspend mode (in Suspend-to-RAM state) use rtcwake command.

rtcwake -d /dev/rtc0 -s 20 -m mem In that example, the system remains in suspended state for 20 seconds before resuming.

Example of Suspend Resume
The following example shows the following steps: Connect to AP root@am180x-evm:~# iw wlan0 connect nisim_ap root@am180x-evm:~# wl1271: Association completed. Enter suspend mode using rtcwake command for 20 seconds root@am180x-evm:~# rtcwake -d /dev/rtc0 -s 20 -m mem Logs shows that the system enters suspend, also that the WLAN connection gets disconnecting wakeup from "mem" at Wed May 18 00:59:18 2011 PM: Syncing filesystems ... done. Freezing user space processes ... (elapsed 0.02 seconds) done. Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done. wl1271: down wl1271: wl1271_suspend: wow_enabled: 0 PM: suspend of devices complete after 260.702 msecs PM: late suspend of devices complete after 0.852 msecs Logs shows that the system is resuming PM: early resume of devices complete after 0.503 msecs wl1271: wl1271 resume Waiting for USB PHY clock good... Waiting for USB PHY clock good... davinci_mdio davinci_mdio.0: resetting idled controller net eth0: attached PHY driver [SMSC LAN8710/LAN8720] (mii_bus:phy_addr=0:00, id=7c0f1) wl1271: firmware booted (Rev 6.1.5.50.69) PM: resume of devices complete after 1088.992 msecs Restarting tasks ... done. cfg80211: Calling CRDA to update world regulatory domain PHY: 0:00 - Link is Up - 100/Full Verify that WLAN connection can be established root@am180x-evm:~# iw wlan0 connect nisim_ap root@am180x-evm:~# wl1271: Association completed.
 * 1) Connect to AP
 * 2) Enter suspend mode using rtcwake command for 20 seconds
 * 3) Logs shows that the system enters suspend, also that the WLAN connection gets disconnecting
 * 4) After 20 Seconds the system will be resumed
 * 5) Logs shows that the system is resuming

External Link
for more information access AM18x Susped-to-RAM mode HOME