linux-kernel - Re: [PATCH 3/6] backlight/pandora: Stop using BL_CORE

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Date:   Wed, 17 Jan 2018 16:47:41 +0000
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Daniel Vetter <daniel.vetter@...ll.ch>,
        DRI Development <dri-devel@...ts.freedesktop.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Daniel Vetter <daniel.vetter@...el.com>
Subject: Re: [PATCH 3/6] backlight/pandora: Stop using BL_CORE_DRIVER1

On 17/01/18 14:01, Daniel Vetter wrote:
> Leaking driver internal tracking into the already massively confusing
> backlight power tracking is really confusing.
> 
> Stop that by allocating a tiny driver private data structure instead.
> 
> Cc: Lee Jones <lee.jones@...aro.org>
> Cc: Daniel Thompson <daniel.thompson@...aro.org>
> Cc: Jingoo Han <jingoohan1@...il.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
> ---
>   drivers/video/backlight/pandora_bl.c | 26 +++++++++++++++++++-------
>   1 file changed, 19 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/video/backlight/pandora_bl.c b/drivers/video/backlight/pandora_bl.c
> index a186bc677c7d..6bd159946a47 100644
> --- a/drivers/video/backlight/pandora_bl.c
> +++ b/drivers/video/backlight/pandora_bl.c
> @@ -35,11 +35,15 @@
>   #define MAX_VALUE 63
>   #define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
>   
> -#define PANDORABL_WAS_OFF BL_CORE_DRIVER1
> +struct pandora_private {
> +	unsigned old_state;
> +#define PANDORABL_WAS_OFF 1

Nit, but we using old_state like a bitfield so, BIT(0)?


> +};
>   
>   static int pandora_backlight_update_status(struct backlight_device *bl)
>   {
>   	int brightness = bl->props.brightness;
> +	struct pandora_private *priv = bl_get_data(bl);
>   	u8 r;
>   
>   	if (bl->props.power != FB_BLANK_UNBLANK)
> @@ -53,7 +57,7 @@ static int pandora_backlight_update_status(struct backlight_device *bl)
>   		brightness = MAX_USER_VALUE;
>   
>   	if (brightness == 0) {
> -		if (bl->props.state & PANDORABL_WAS_OFF)
> +		if (priv->old_state & PANDORABL_WAS_OFF)
>   			goto done;
>   
>   		/* first disable PWM0 output, then clock */
> @@ -66,7 +70,7 @@ static int pandora_backlight_update_status(struct backlight_device *bl)
>   		goto done;
>   	}
>   
> -	if (bl->props.state & PANDORABL_WAS_OFF) {
> +	if (priv->old_state & PANDORABL_WAS_OFF) {
>   		/*
>   		 * set PWM duty cycle to max. TPS61161 seems to use this
>   		 * to calibrate it's PWM sensitivity when it starts.
> @@ -93,9 +97,9 @@ static int pandora_backlight_update_status(struct backlight_device *bl)
>   
>   done:
>   	if (brightness != 0)
> -		bl->props.state &= ~PANDORABL_WAS_OFF;
> +		priv->old_state 0;
>   	else
> -		bl->props.state |= PANDORABL_WAS_OFF;
> +		priv->old_state = PANDORABL_WAS_OFF;

Well, we were using it like a bitfield until this bit...


>   
>   	return 0;
>   }
> @@ -109,15 +113,23 @@ static int pandora_backlight_probe(struct platform_device *pdev)
>   {
>   	struct backlight_properties props;
>   	struct backlight_device *bl;
> +	struct pandora_private *priv;
>   	u8 r;
>   
> +	priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv) {
> +		dev_err(&pdev->dev, "failed to allocate driver private data\n");
> +		return -ENOMEM;
> +	}
> +
>   	memset(&props, 0, sizeof(props));
>   	props.max_brightness = MAX_USER_VALUE;
>   	props.type = BACKLIGHT_RAW;
>   	bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
> -					NULL, &pandora_backlight_ops, &props);
> +					priv, &pandora_backlight_ops, &props);
>   	if (IS_ERR(bl)) {
>   		dev_err(&pdev->dev, "failed to register backlight\n");
> +		kfree(priv);

Why can't we rely on devres for cleanup?


>   		return PTR_ERR(bl);
>   	}
>   
> @@ -126,7 +138,7 @@ static int pandora_backlight_probe(struct platform_device *pdev)
>   	/* 64 cycle period, ON position 0 */
>   	twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
>   
> -	bl->props.state |= PANDORABL_WAS_OFF;
> +	priv->old_state = PANDORABL_WAS_OFF;
>   	bl->props.brightness = MAX_USER_VALUE;
>   	backlight_update_status(bl);
>   
>