linux-kernel - Re: [PATCH v2 06/10] clk: renesas: rzg2l: Extend power domain support

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Date: Thu, 14 Mar 2024 16:59:57 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Claudiu <claudiu.beznea@...on.dev>
Cc: mturquette@...libre.com, sboyd@...nel.org, robh@...nel.org, 
	krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, magnus.damm@...il.com, 
	linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH v2 06/10] clk: renesas: rzg2l: Extend power domain support

Hi Claudiu,

On Thu, Mar 7, 2024 at 3:07 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.
>
> Apart from MSTOP support, RZ/G3S can save more power by powering down the
> individual IPs (after MSTOP has been set) if proper bits in
> CPG_PWRDN_IP{1,2} registers are set.
>
> The MSTOP and IP power down support were 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:
> - called pm_genpd_init() with proper value for is_off argument
> - fixed typos
> - used flexible array for struct rzg2l_cpg_pm_domains::domains member
> - moved genpd member of struct rzg2l_cpg_pd at the beginning of struct
> - didn't initialize the parent variable in rzg2l_cpg_add_pm_domains()
>   as it is already initialized in the for block from
>   rzg2l_cpg_add_pm_domains() and that initialization should be enough
> - dropped RZG2L_PD_F_PARENT flag
> - used datasheet naming for all MSTOP registers
> - added all MSTOP registers to rzg2l-cpg.h
> - reworked the code that initializes the register offset and bits for domains
> - dropped MSTOP*(), PWRDN*() macros and introduced struct rzg2l_cpg_reg_conf
>   and DEF_REG_CONF() for domain description
> - constified the 1st argument of rzg2l_cpg_pm_domain_xlate()
> - used dev instead of priv->dev where possible
> - dropped RZG2L_PD_F_PARENT
> - added RZG2L_PD_F_NONE for better description of domains in platform
>   specific clock drivers

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