Re: [PATCH v5 resend 4/4] drivers: clk: renesas: ignore all clocks which are assigned to non-Linux system

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On Wed, Jan 10, 2024 at 2:15 AM Kuninori Morimoto
<kuninori.morimoto.gx@xxxxxxxxxxx> wrote:
> Some boards might use Linux and another OS at the same time. In such
> case, currently, during booting, Linux will stop necessary module clocks
> which are not used on the Linux side, but are used by another OS.
>
> To avoid such situation, renesas-cpg-mssr tries to find
> status = "reserved" devices (A), and adds CLK_IGNORE_UNUSED flag to its
> <&cgp CPG_MOD xxx> clock (B).
>
> Table 2.4: Values for status property
> https://github.com/devicetree-org/devicetree-specification/releases/download/v0.4/devicetree-specification-v0.4.pdf
>
> "reserved"
>         Indicates that the device is operational, but should not be
>         used. Typically this is used for devices that are controlled
>         by another software component, such as platform firmware.
>
> ex)
>         scif5: serial@e6f30000 {
>                 ...
> (B)             clocks = <&cpg CPG_MOD 202>,
>                          <&cpg CPG_CORE R8A7795_CLK_S3D1>,
>                          <&scif_clk>;
>                 ...
> (A)             status = "reserved";
>         };
>
> Cc: Aymeric Aillet <aymeric.aillet@xxxxxxx>
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
> Tested-by: Yusuke Goda <yusuke.goda.sx@xxxxxxxxxxx>

Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds





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