linux-kernel - Re: [PATCH v2] mfd: syscon: Use a unique name with regmap

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Message-ID: <217993e5-5e1d-79a1-7684-c6bb964379f0@lechnology.com>
Date:   Mon, 27 Jan 2020 17:40:54 -0600
From:   David Lechner <david@...hnology.com>
To:     Suman Anna <s-anna@...com>, Lee Jones <lee.jones@...aro.org>
Cc:     Arnd Bergmann <arnd@...db.de>, Tony Lindgren <tony@...mide.com>,
        Roger Quadros <rogerq@...com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH v2] mfd: syscon: Use a unique name with regmap_config

On 1/27/20 5:12 PM, Suman Anna wrote:
> The DT node full name is currently being used in regmap_config
> which in turn is used to create the regmap debugfs directories.
> This name however is not guaranteed to be unique and the regmap
> debugfs registration can fail in the cases where the syscon nodes
> have the same unit-address but are present in different DT node
> hierarchies. Replace this logic using the syscon reg resource
> address instead (inspired from logic used while creating platform
> devices) to ensure a unique name is given for each syscon.
> 
> Signed-off-by: Suman Anna <s-anna@...com>
> ---
> v2: Fix build warning reported by kbuild test bot
> v1: https://patchwork.kernel.org/patch/11346363/
> 
>   drivers/mfd/syscon.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
> index e22197c832e8..f0815d8e6e95 100644
> --- a/drivers/mfd/syscon.c
> +++ b/drivers/mfd/syscon.c
> @@ -101,12 +101,14 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk)
>   		}
>   	}
>   
> -	syscon_config.name = of_node_full_name(np);
> +	syscon_config.name = kasprintf(GFP_KERNEL, "%pOFn@...x", np,
> +				       (u64)res.start);

Would it make sense to also include the node name along with the
pointer address so that the name is still easily identifiable?

>   	syscon_config.reg_stride = reg_io_width;
>   	syscon_config.val_bits = reg_io_width * 8;
>   	syscon_config.max_register = resource_size(&res) - reg_io_width;
>   
>   	regmap = regmap_init_mmio(NULL, base, &syscon_config);
> +	kfree(syscon_config.name);
>   	if (IS_ERR(regmap)) {
>   		pr_err("regmap init failed\n");
>   		ret = PTR_ERR(regmap);
>