Re: [PATCH v13 0/5] firmware: ti_sci: Introduce system suspend support

[Roger Quadros <rogerq@kernel.org>]

Hi Markus

On 07/10/2024 09:08, Markus Schneider-Pargmann wrote:
> Abstract
> ********
> 
> This series introduces necessary ti_sci driver functionality to support
> various Suspend-to-RAM modes on TI AM62 family of devices. These Low
> Power Modes include Deep Sleep and MCU Only as described in section
> "6.2.4 Power Modes" of the AM62P Technical Reference Manual [0].
> 
> Summary
> *******
> 
> This series is a restructuring and rebase of the patch series by
> Dave Gerlach [1] and Dhruva Gole [2]. It applies on top of Linux
> 6.12-rc1.
> 
> The kernel triggers entry to Low Power Mode through the mem suspend
> transition with the following:
> 
> * At the  bootloader stage, one is  expected to package the  TIFS stub
>   which then gets  pulled into the Tightly coupled memory  of the Device
>   Mgr  (DM) R5  when it  starts up.  If using  U-Boot, then  it requires
>   tispl.bin to contain the TIFS stub. Refer to documentation in upstream
>   u-boot[3] for further details. The  supported firmware version is from
>   TI Processor SDK >= 10.00 ie. tag 10.00.04 from ti-linux-firmware [4].
> 
> * Use a TF-A binary that supports PSCI_SYSTEM_SUSPEND call. This causes
>   system to use PSCI system suspend as last step of mem sleep.
> 
> * We add support for the TISCI_MSG_QUERY_FW_CAPS message, used to retrieve
>   the firmware capabilities of the currently running system firmware [6].
>   Sysfw version >= 10.00.04 support LPM_DM_MANAGED capability, where
>   Device Mgr firmware now manages which low power mode is chosen. Going
>   forward, this is the default configuration supported for TI AM62 family
>   of devices. The state chosen by the DM can be influenced by sending
>   constraints using the new LPM constraint APIs. (Patch 1)
> 
> * The firmware requires that the OS sends a TISCI_MSG_PREPARE_SLEEP
>   message in order to provide details about suspend. The ti_sci driver
>   must send this message to firmware with the above information
>   included, which it does during the driver suspend handler when
>   PM_MEM_SUSPEND is the determined state being entered. The mode being
>   sent depends on whether firmware capabilities have support for
>   LPM_DM_MANAGED feature. Legacy firmware or those supporting other
>   modes can extend the mode selection logic as needed. (Patch 2)
> 
> * We also add the remaining TISCI Low Power Mode messages required for
>   inquiring wake reason and managing LPM constraints as part of a new PM
>   ops. These messages are part of the TISCI PM Low Power Mode API [5].
>   (Patch 3)
> 
> * Finally if any CPUs have PM QoS resume latency constraints set, we
>   aggregate these and set the TISCI system-wide latency constraint.
>   (Patch 4)
> 
> Testing
> *******
> 
> This series can for example be tested with a am62a-lp-sk board.

Tested on am62-sk.

Tested-by: Roger Quadros <rogerq@kernel.org>

> 
> For am62a-lp-sk all usb nodes have to be disabled at the moment (usbss0,
> usb0, usbss1 and usb1). There is currently an issue with USB Link Power
> Management and turning off the USB device which is being worked on.

Or you can this patch [1].

[1] https://lore.kernel.org/all/20241009-am62-lpm-usb-v2-1-da26c0cd2b1e@kernel.org/

cheers,
-roger
-- 
cheers,
-roger