Re: [PATCH] arm64: dts: ti: k3-j784s4: use ti,j7200-padconf compatible

[Thomas Richard <thomas.richard@bootlin.com>]

On 12/4/24 10:59, Francesco Dolcini wrote:
> Hello Thomas,
> thanks for the update.
> 
> On Wed, Dec 04, 2024 at 10:08:43AM +0100, Thomas Richard wrote:
>> On 11/19/24 20:01, Francesco Dolcini wrote:
>>> Hello Thomas and TI folks,
>>>
>>> On Wed, Nov 13, 2024 at 11:43:05AM +0100, Thomas Richard wrote:
>>>> Like on j7200, pinctrl contexts shall be saved and restored during
>>>> suspend-to-ram.
>>>>
>>>> So use ti,j7200-padconf compatible.
>>>>
>>>> Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
>>>> ---
>>>> Use ti,j7200-padconf compatible to save and restore pinctrl contexts during
>>>> suspend-to-ram.
>>>> ---
>>>>  arch/arm64/boot/dts/ti/k3-j784s4-main.dtsi       |  6 +++---
>>>>  arch/arm64/boot/dts/ti/k3-j784s4-mcu-wakeup.dtsi | 12 ++++++------
>>>
>>> Do j784s4 supports any kind of low power mode and/or suspend to ram? My
>>> understanding was that this was not supported, but maybe there is some
>>> details that was lost when I was told this information.
>>
>> We are working on suspend-to-ram support for j7200 and j784s4.
>> During suspend-to-ram the SoC is fully powered-off (thanks to the PMIC
>> which powers off all the power rails except the DDR which is in
>> self-refresh), like on j7200.
>> Please let me know if you want more details.
> 
> ok, that's quite different from the common suspend-to-ram we use to have
> implemented on other SoC. You would have some boot firmware (likely U-Boot)
> code executing during resume, taking some different code path, in a similar way
> to what it is being done for the partial-io support on am62p. It's going to be
> more similar to hibernation from some point of view.

If you want more details you can have a look to this presentation [1]
(from my colleague Gregory CLEMENT).

[1] https://www.youtube.com/watch?v=sN4krurp8bM

> 
> Do you expect to have this feature nicely integrated within the standard
> suspend/resume "framework" in Linux?

Yes.

Regards,

Thomas