linux-kernel - Re: [PATCH V3 0/2] clk: imx: introduce fsl,always-on-clocks

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Message-ID: <13097869.uLZWGnKmhe@steina-w>
Date:   Tue, 13 Sep 2022 12:03:07 +0200
From:   Alexander Stein <alexander.stein@...tq-group.com>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc:     krzysztof.kozlowski+dt@...aro.org, robh+dt@...nel.org,
        abelvesa@...nel.org, abel.vesa@...aro.org, mturquette@...libre.com,
        sboyd@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
        kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH V3 0/2] clk: imx: introduce fsl,always-on-clocks

Hello,

Am Dienstag, 13. September 2022, 11:21:34 CEST schrieb Peng Fan (OSS):
> From: Peng Fan <peng.fan@....com>
> 
> V3:
>  Rename to fsl,always-on-clocks
> 
> V2:
>  Use protected-clocks
>  https://lore.kernel.org/all/20220816130327.2987710-1-peng.fan@oss.nxp.com/
> 
> V1:
>  Use fsl,protected-clocks
>  https://lore.kernel.org/all/20220815033632.1687854-1-peng.fan@oss.nxp.com/
> 
> There are two cases that I wanna this property could serve:
> Virtualization: root cell linux run in parallel with inmate cell
> AMP: M7/4 runs in parallel with A53
> 
> The major case is:
> Jailhouse hypervisor only support partition, so devices are partitioned.
> But there is only CCM module that provides clock, the CCM is handled by
> root cell linux, need make sure the root cell linux not shutdown the
> clocks using by inmate cell.
> 
> I was thinking whether need to provide a rate entry to ask root cell
> configure the clk rate for inmate cell. But NXP downstream not have it,
> see
> https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/clk/imx/c
> lk-imx8mp.c?h=lf-5.15.y#n690 So just leave the property as uint32-array.
> 
> This patchset could also benifit AMP case, check the two commits
> commit 19565ea12d61 ("clk: imx: add mcore_booted module paratemter")
> commit d097cc045b64 ("clk: imx8mp: remove SYS PLL 1/2 clock gates")
> Although I not plan to drop the upper two patches, this patchset
> exposes opportunity for better power consumption.

Has this the same intention/effect as 'critical-clocks' from [1]? I guess in 
both cases you want to keep clocks enabled, even though there is no (local) 
user.

Best regards,
Alexander

[1] https://lore.kernel.org/linux-clk/20220517235919.200375-1-marex@denx.de/

> Peng Fan (2):
>   dt-bindings: clock: imx8m/imx93: introduce fsl,always-on-clocks
>     property
>   clk: imx: support fsl,always-on-clocks
> 
>  .../bindings/clock/imx8m-clock.yaml           |  4 ++++
>  .../bindings/clock/imx93-clock.yaml           |  4 ++++
>  drivers/clk/imx/clk-imx8mm.c                  |  2 ++
>  drivers/clk/imx/clk-imx8mn.c                  |  2 ++
>  drivers/clk/imx/clk-imx8mp.c                  |  2 ++
>  drivers/clk/imx/clk-imx8mq.c                  |  2 ++
>  drivers/clk/imx/clk.c                         | 21 +++++++++++++++++++
>  drivers/clk/imx/clk.h                         |  2 ++
>  8 files changed, 39 insertions(+)