linux-kernel - Re: [PATCH v6 0/3] pmdomain: ti_sci: collect and send low-power mode constraints

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Message-ID: <CAPDyKFo9N8M73Z6Ltsbnd-WR-jYAqBedAHndViSD7YaKKYgBsA@mail.gmail.com>
Date: Tue, 10 Dec 2024 15:02:04 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Kevin Hilman <khilman@...libre.com>
Cc: linux-pm@...r.kernel.org, Nishanth Menon <nm@...com>, Dhruva Gole <d-gole@...com>, 
	Akashdeep Kaur <a-kaur@...com>, Sebin Francis <sebin.francis@...com>, 
	Markus Schneider-Pargmann <msp@...libre.com>, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 0/3] pmdomain: ti_sci: collect and send low-power mode constraints

On Fri, 6 Dec 2024 at 23:13, Kevin Hilman <khilman@...libre.com> wrote:
>
> The latest (10.x) version of the firmware for the PM co-processor (aka
> device manager, or DM) adds support for a "managed" mode, where the DM
> firmware will select the specific low power state which is entered
> when Linux requests a system-wide suspend.
>
> In this mode, the DM will always attempt the deepest low-power state
> available for the SoC.
>
> However, Linux (or OSes running on other cores) may want to constrain
> the DM for certain use cases.  For example, the deepest state may have
> a wakeup/resume latency that is too long for certain use cases.  Or,
> some wakeup-capable devices may potentially be powered off in deep
> low-power states, but if one of those devices is enabled as a wakeup
> source, it should not be powered off.
>
> These kinds of constraints are are already known in Linux by the use
> of existing APIs such as per-device PM QoS and device wakeup APIs, but
> now we need to communicate these constraints to the DM.
>
> For TI SoCs with TI SCI support, all DM-managed devices will be
> connected to a TI SCI PM domain.  So the goal of this series is to use
> the PM domain driver for TI SCI devices to collect constraints, and
> communicate them to the DM via the new TI SCI APIs.
>
> This is all managed by TI SCI PM domain code.  No new APIs are needed
> by Linux drivers.  Any device that is managed by TI SCI will be
> checked for QoS constraints or wakeup capability and the constraints
> will be collected and sent to the DM.
>
> This series depends on the support for the new TI SCI APIs (v10) and
> was also tested with this series to update 8250_omap serial support
> for AM62x[2].
>
> [1] https://lore.kernel.org/all/20240801195422.2296347-1-msp@baylibre.com
> [2] https://lore.kernel.org/all/20240807141227.1093006-1-msp@baylibre.com/
>
> Signed-off-by: Kevin Hilman <khilman@...libre.com>
> ---
> Changes in v6:
> - fix build warning on arm32 when building with W=1 and CONFIG_PM_SLEEP=n
> - rebase onto v6.13-rc1
> - fix latency units: convert usecs (PM QoS) to msecs (TI SCI)
> - all dependencies are now merged in v6.13-rc1
> - Link to v5: https://lore.kernel.org/r/20241101-lpm-v6-10-constraints-pmdomain-v5-0-3011aa04622f@baylibre.com

v6 applied for next and by amending patch1 to deal with the sorting of
include files, thanks!

[...]

Kind regards
Uffe