linux-kernel - Re: [PATCH v2 1/6] pinctrl: sunxi: support pin controllers with holes among IRQ banks

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Date:   Wed, 7 Feb 2018 09:51:46 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Icenowy Zheng <icenowy@...c.io>
Cc:     Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 1/6] pinctrl: sunxi: support pin controllers with
 holes among IRQ banks

Hi,

On Sat, Feb 03, 2018 at 11:49:37PM +0800, Icenowy Zheng wrote:
> diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.h b/drivers/pinctrl/sunxi/pinctrl-sunxi.h
> index 11b128f54ed2..fae732c8c548 100644
> --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.h
> +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.h
> @@ -110,7 +110,7 @@ struct sunxi_pinctrl_desc {
>  	int				npins;
>  	unsigned			pin_base;
>  	unsigned			irq_banks;
> -	unsigned			irq_bank_base;
> +	const unsigned int		*irq_bank_map;
>  	bool				irq_read_needs_mux;
>  	bool				disable_strict_mode;
>  };
> @@ -263,12 +263,21 @@ static inline u32 sunxi_pull_offset(u16 pin)
>  	return pin_num * PULL_PINS_BITS;
>  }
>  
> -static inline u32 sunxi_irq_cfg_reg(u16 irq, unsigned bank_base)
> +static inline u32 sunxi_irq_hw_bank_num(u8 bank, const unsigned int *bank_map)
> +{
> +	if (!bank_map)
> +		return bank;
> +	else
> +		return bank_map[bank];
> +}

From a function API PoV, I guess it would make more sense and be
cleaner to simply pass the sunxi_pinctrl_desc structure (as the first
argument) and have the function there read that structure and act upon
it.

Giving it just a blank pointer, without any size indication, and
either dereferencing it without any boundary check, or changing the
behaviour based on whether it's null or not seems pretty fragile.

I guess you could do it in two patches. One to change the function
prototypes to call the sunxi_irq_cfg_reg function (and all its caller)
to have the prototype (struct sunxi_pinctrl_desc *desc, u16 irq).

And then in a later patch change the behaviour to introduce the map.

Thanks!
Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com

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