Part Number: AM4372
Hi TI
A customer is testing Power Saving Mode Entry and Sleep with RTC.
Their system is powered by connecting PC and USB, and aims to wake up via USB in a sleep state.
They are currently having a hard time waking up through USB event from sleep mode, so I am inquiring.
Q1. According to TRM, Resume is possible through PHY WakeUP from Standby Sleep state in USB Suspend/Resume Use Case, is this function working in current SDK?
Q2. In the USB Suspend/Resume Use Case above, I would like to ask you to explain exactly what the Clock Gated state of the USB Controller State is.
Q3. In Linux power management, please check if the mem_sleep state is in the same sleep state as the AM437x manual says when the mem_sleep state is deep as shown below.
am437x-aum100 login: root
root@am437x-aum100:~# cat /sys/power/mem_sleep
s2idle shallow [deep]
root@am437x-aum100:~# echo mem > /sys/power/state
[ 27.870367] PM: suspend entry (deep)
[ 27.873997] PM: Syncing filesystems ... done.
[ 27.973787] Freezing user space processes ... (elapsed 0.001 seconds) done.
[ 27.982472] OOM killer disabled.
[ 27.985729] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
[ 27.994826] Suspending console(s) (use no_console_suspend to debug)
[ 28.035114] GIC and Wakeupgen context save failed
[ 28.035114] pm33xx pm33xx: PM: Successfully put all powerdomains to target state
[ 28.035114] PM: Wakeup source UART
[ 28.063903] OOM killer enabled.
[ 28.067082] Restarting tasks ... done.
[ 28.072094] PM: suspend exit
Q4. Last year, after a long inquiry, TI concluded that Linux's power management is activated only when RTC is connected, so they are currently doing PM actions after RTC connection.
By the way, according to the description at the top of page 261 of the Technical Reference Manual as below, power reduction can be performed without RTC.
To save the unit price of mass production, please check again whether it is possible to perform a sleep operation without RTC.
Thanks.
Regards,
Jack
