linux-kernel - Re: [PATCH v2 2/2] backlight: aw99706: Add support for Awinic AW99706 backlight

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Message-ID: <20251104-attractive-dragonfly-of-perspective-0d52d6@kuoka>
Date: Tue, 4 Nov 2025 08:36:04 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Junjie Cao <caojunjie650@...il.com>
Cc: Lee Jones <lee@...nel.org>, Daniel Thompson <danielt@...nel.org>, 
	Jingoo Han <jingoohan1@...il.com>, Pavel Machek <pavel@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Helge Deller <deller@....de>, 
	dri-devel@...ts.freedesktop.org, linux-leds@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org, Pengyu Luo <mitltlatltl@...il.com>
Subject: Re: [PATCH v2 2/2] backlight: aw99706: Add support for Awinic
 AW99706 backlight

On Mon, Nov 03, 2025 at 07:06:48PM +0800, Junjie Cao wrote:
> +struct reg_init_data;
> +
> +struct aw99706_device {
> +	struct i2c_client *client;
> +	struct device *dev;
> +	struct regmap *regmap;
> +	struct backlight_device *bl_dev;
> +	struct gpio_desc *hwen_gpio;
> +	struct reg_init_data *init_tbl;
> +	int init_tbl_size;
> +	bool bl_enable;
> +};
> +
> +enum reg_access {
> +	REG_NONE_ACCESS	= 0,
> +	REG_RD_ACCESS	= 1,
> +	REG_WR_ACCESS	= 2,
> +};
> +
> +const u8 aw99706_regs[AW99706_REG_MAX + 1] = {

Why isn't this static?

> +	[AW99706_CFG0_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFG1_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFG2_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFG3_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFG4_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFG5_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFG6_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFG7_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFG8_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFG9_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFGA_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFGB_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFGC_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_CFGD_REG]		= REG_RD_ACCESS | REG_WR_ACCESS,
> +	[AW99706_FLAG_REG]		= REG_RD_ACCESS,
> +	[AW99706_CHIPID_REG]		= REG_RD_ACCESS,
> +	[AW99706_LED_OPEN_FLAG_REG]	= REG_RD_ACCESS,
> +	[AW99706_LED_SHORT_FLAG_REG]	= REG_RD_ACCESS,
> +
> +	/*
> +	 * Write bit is dropped here, writing BIT(0) to MTPLDOSEL will unlock
> +	 * Multi-time Programmable (MTP).
> +	 */
> +	[AW99706_MTPLDOSEL_REG]		= REG_RD_ACCESS,
> +	[AW99706_MTPRUN_REG]		= REG_NONE_ACCESS,
> +};
> +

...

> +	aw = devm_kzalloc(dev, sizeof(*aw), GFP_KERNEL);
> +	if (!aw)
> +		return -ENOMEM;
> +
> +	aw->client = client;
> +	aw->dev = dev;
> +	i2c_set_clientdata(client, aw);
> +
> +	aw->regmap = devm_regmap_init_i2c(client, &aw99706_regmap_config);
> +	if (IS_ERR(aw->regmap))
> +		return dev_err_probe(dev, PTR_ERR(aw->regmap),
> +				     "Failed to init regmap\n");
> +
> +	ret = aw99706_chip_id_read(aw);
> +	if (ret != AW99706_ID)
> +		return dev_err_probe(dev, ret,
> +				     "Failed to validate chip id\n")

Why are you exiting the probe with a positive value like 4 or 8? This
makes no sense. Registers do not coontain Linux return codes.

Best regards,
Krzysztof