linux-kernel - Re: [PATCH v4] dt-bindings: pinctrl: renesas: Document RZ/V2H(P) SoC

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Date: Mon, 10 Jun 2024 16:00:50 -0600
From: "Rob Herring (Arm)" <robh@...nel.org>
To: Prabhakar <prabhakar.csengg@...il.com>
Cc: devicetree@...r.kernel.org,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
	linux-renesas-soc@...r.kernel.org, linux-gpio@...r.kernel.org,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Magnus Damm <magnus.damm@...il.com>,
	Conor Dooley <conor+dt@...nel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	linux-kernel@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v4] dt-bindings: pinctrl: renesas: Document RZ/V2H(P) SoC


On Thu, 06 Jun 2024 09:51:33 +0100, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> 
> Add documentation for the pin controller found on the Renesas RZ/V2H(P)
> (R9A09G057) SoC. The RZ/V2H PFC varies slightly compared to the RZ/G2L
> family:
> - Additional bits need to be set during pinmuxing.
> - The GPIO pin count is different.
> 
> Hence, a SoC-specific compatible string, 'renesas,r9a09g057-pinctrl', is
> added for the RZ/V2H(P) SoC.
> 
> Also, add the 'renesas,output-impedance' property. The drive strength
> setting on RZ/V2H(P) depends on the different power rails coming out from
> the PMIC (connected via I2C). These power rails (required for drive
> strength) can be 1.2V, 1.8V, or 3.3V.
> 
> Pins are grouped into 4 groups:
> 
> Group 1: Impedance
> - 150/75/38/25 ohms (at 3.3V)
> - 130/65/33/22 ohms (at 1.8V)
> 
> Group 2: Impedance
> - 50/40/33/25 ohms (at 1.8V)
> 
> Group 3: Impedance
> - 150/75/37.5/25 ohms (at 3.3V)
> - 130/65/33/22 ohms (at 1.8V)
> 
> Group 4: Impedance
> - 110/55/30/20 ohms (at 1.8V)
> - 150/75/38/25 ohms (at 1.2V)
> 
> The 'renesas,output-impedance' property, as documented, can be
> [0, 1, 2, 3], these correspond to register bit values that can
> be set in the PFC_IOLH_mn register, which adjusts the drive
> strength value and is pin-dependent.
> 
> As power rail information may not be available very early in the boot
> process, the 'renesas,output-impedance' property is added instead of
> reusing the 'output-impedance-ohms' property.
> 
> Also, allow bias-disable, bias-pull-down and bias-pull-up properties
> as these can be used to configure the pins.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
> Sending just the binding patch of series [0] as reset of the patches have
> been Reviewed.
> 
> [0] https://patchwork.kernel.org/project/linux-renesas-soc/cover/20240530173857.164073-1-prabhakar.mahadev-lad.rj@bp.renesas.com/
> 
> v3->v4
> - Added a conditional schema for ensuring the reset length
>   is 2 for RZ/V2H and 3 otherwise
> - Updated description for renesas,output-impedance property
> - Dropped '|'
> 
> v2->v3
> - Updated description for renesas,output-impedance property
> - Updated commit description
> 
> RFC->v2
> - Renamed renesas-rzv2h,output-impedance -> renesas,output-impedance
> - Updated values for renesas,output-impedance
> - Added bias properties
> ---
>  .../pinctrl/renesas,rzg2l-pinctrl.yaml        | 37 +++++++++++++++++--
>  1 file changed, 33 insertions(+), 4 deletions(-)
> 

Reviewed-by: Rob Herring (Arm) <robh@...nel.org>