linux-kernel - Re: [PATCH v2 05/10] soc: sunxi: sram: Fix probe function ordering issues

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Date:   Mon, 15 Aug 2022 16:06:27 +0200
From:   Heiko Stübner <heiko@...ech.de>
To:     Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     Samuel Holland <samuel@...lland.org>,
        Arnd Bergmann <arnd@...db.de>,
        Hans de Goede <hdegoede@...hat.com>,
        Icenowy Zheng <icenowy@...c.io>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Maxime Ripard <mripard@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...ts.linux.dev, Samuel Holland <samuel@...lland.org>
Subject: Re: [PATCH v2 05/10] soc: sunxi: sram: Fix probe function ordering issues

Am Montag, 15. August 2022, 06:12:42 CEST schrieb Samuel Holland:
> Errors from debugfs are intended to be non-fatal, and should not prevent
> the driver from probing.
> 
> Since debugfs file creation is treated as infallible, move it below the
> parts of the probe function that can fail. This prevents an error
> elsewhere in the probe function from causing the file to leak. Do the
> same for the call to of_platform_populate().
> 
> Finally, checkpatch suggests an octal literal for the file permissions.
> 
> Fixes: 4af34b572a85 ("drivers: soc: sunxi: Introduce SoC driver to map SRAMs")
> Fixes: 5828729bebbb ("soc: sunxi: export a regmap for EMAC clock reg on A64")
> Reviewed-by: Jernej Skrabec <jernej.skrabec@...il.com>
> Signed-off-by: Samuel Holland <samuel@...lland.org>

Tested-by: Heiko Stuebner <heiko@...ech.de>

but one thing below

> ---
> 
> (no changes since v1)
> 
>  drivers/soc/sunxi/sunxi_sram.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/soc/sunxi/sunxi_sram.c b/drivers/soc/sunxi/sunxi_sram.c
> index a858a37fcdd4..52d07bed7664 100644
> --- a/drivers/soc/sunxi/sunxi_sram.c
> +++ b/drivers/soc/sunxi/sunxi_sram.c
> @@ -332,9 +332,9 @@ static struct regmap_config sunxi_sram_emac_clock_regmap = {
>  
>  static int __init sunxi_sram_probe(struct platform_device *pdev)
>  {
> -	struct dentry *d;
>  	struct regmap *emac_clock;
>  	const struct sunxi_sramc_variant *variant;
> +	struct device *dev = &pdev->dev;
>  
>  	sram_dev = &pdev->dev;
>  
> @@ -346,13 +346,6 @@ static int __init sunxi_sram_probe(struct platform_device *pdev)
>  	if (IS_ERR(base))
>  		return PTR_ERR(base);
>  
> -	of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
> -
> -	d = debugfs_create_file("sram", S_IRUGO, NULL, NULL,
> -				&sunxi_sram_fops);
> -	if (!d)
> -		return -ENOMEM;
> -
>  	if (variant->num_emac_clocks > 0) {
>  		emac_clock = devm_regmap_init_mmio(&pdev->dev, base,
>  						   &sunxi_sram_emac_clock_regmap);
> @@ -361,6 +354,10 @@ static int __init sunxi_sram_probe(struct platform_device *pdev)
>  			return PTR_ERR(emac_clock);
>  	}
>  
> +	of_platform_populate(dev->of_node, NULL, NULL, dev);

hmm, of_platform_populate() can actually fail [0] it just looks a bit like
sunxi driver seem to ignore that by {chance, design?} [1] .

So I guess this might want to have handling for probably unlikely
possible errors instead?


Heiko

[0] https://elixir.bootlin.com/linux/latest/source/drivers/of/platform.c#L463
[1] https://elixir.bootlin.com/linux/latest/source/drivers/bus/sun50i-de2.c#L22
> +
> +	debugfs_create_file("sram", 0444, NULL, NULL, &sunxi_sram_fops);
> +
>  	return 0;
>  }
>  
>