linux-kernel - Re: [PATCH v4 6/8] clk: renesas: rzg2l: Extend power domain support

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Date: Wed, 24 Apr 2024 16:09:58 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Claudiu <claudiu.beznea@...on.dev>
Cc: mturquette@...libre.com, robh@...nel.org, krzk+dt@...nel.org, 
	conor+dt@...nel.org, magnus.damm@...il.com, ulf.hansson@...aro.org, 
	linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org, Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH v4 6/8] clk: renesas: rzg2l: Extend power domain support

On Mon, Apr 22, 2024 at 12:54 PM Claudiu <claudiu.beznea@...on.dev> wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>
> RZ/{G2L, V2L, G3S}-based CPG versions have support for saving extra
> power when clocks are disabled by activating module standby. This is done
> through MSTOP-specific registers that are part of CPG. Each individual
> module has one or more bits associated with one MSTOP register (see table
> "Registers for Module Standby Mode" from HW manuals). Hardware manual
> associates modules' clocks with one or more MSTOP bits. There are 3
> mappings available (identified by researching RZ/G2L, RZ/G3S, RZ/V2L HW
> manuals):
>
> case 1: N clocks mapped to N MSTOP bits (with N={0, ..., X})
> case 2: N clocks mapped to 1 MSTOP bit  (with N={0, ..., X})
> case 3: N clocks mapped to M MSTOP bits (with N={0, ..., X}, M={0, .., Y})
>
> Case 3 has been currently identified on RZ/V2L for the VCPL4 module.
>
> To cover all three cases, the individual platform drivers will provide to
> clock driver MSTOP register offset and associated bits in this register
> as a bitmask and the clock driver will apply this bitmask to proper
> MSTOP register.
>
> The MSTOP was implemented through power domains. Platform-specific clock
> drivers will register an array of type
> struct rzg2l_cpg_pm_domain_init_data, which will be used to instantiate
> properly the power domains.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> ---
>
> Changes in v2:

s/v2/v4/

> - dropped the pwrdn functionality until it is better understanded;
>   at the same time kept the code ready for pwrd being added by keeping
>   struct rzg2l_cpg_pm_domain_conf, DEF_REG_CONF(); please let me know
>   if you prefer otherwise
> - @Geert, @Ulf: I dropped your previous Rb tags due to dropping pwrdn

Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68korg

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