linux-kernel - Re: [PATCH V4 8/8] backlight: qcom-wled: Add auto string detection logic

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Message-ID: <20180807063229.GE23866@tuxbook-pro>
Date:   Mon, 6 Aug 2018 23:32:29 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Kiran Gunda <kgunda@...eaurora.org>
Cc:     jingoohan1@...il.com, lee.jones@...aro.org,
        b.zolnierkie@...sung.com, dri-devel@...ts.freedesktop.org,
        daniel.thompson@...aro.org, jacek.anaszewski@...il.com,
        pavel@....cz, robh+dt@...nel.org, mark.rutland@....com,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH V4 8/8] backlight: qcom-wled: Add auto string detection
 logic

On Mon 09 Jul 03:22 PDT 2018, Kiran Gunda wrote:
> diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
[..]
> @@ -189,6 +206,15 @@ static int wled4_set_brightness(struct wled *wled, u16 brightness)
>  	return 0;
>  }
>  
> +static void wled_ovp_work(struct work_struct *work)
> +{
> +	struct wled *wled = container_of(work,
> +					 struct wled, ovp_work.work);
> +
> +	if (wled->ovp_irq > 0)
> +		enable_irq(wled->ovp_irq);
> +}
> +
>  static int wled_module_enable(struct wled *wled, int val)
>  {
>  	int rc;
> @@ -200,7 +226,18 @@ static int wled_module_enable(struct wled *wled, int val)
>  				WLED_CTRL_REG_MOD_EN,
>  				WLED_CTRL_REG_MOD_EN_MASK,
>  				val << WLED_CTRL_REG_MOD_EN_SHIFT);
> -	return rc;
> +	if (rc < 0)
> +		return rc;
> +
> +	if (val) {
> +		schedule_delayed_work(&wled->ovp_work, WLED_SOFT_START_DLY_US);

schedule_delayed_work() takes a delay in jiffies, not micro seconds.

> +	} else {
> +		cancel_delayed_work_sync(&wled->ovp_work);

If we get here within WLED_SOFT_START_DLY_US of a module enable we have
yet to execute the enable_irq() in the delayed worker, which should mean
that the irq is unbalanced from then on.

I believe you can check the return value of cancel_delayed_work_sync()
being true to know if wled_ovp_work() was yet to execute.

> +		if (wled->ovp_irq > 0)
> +			disable_irq(wled->ovp_irq);
> +	}
> +
> +	return 0;
>  }
>  

Regards,
Bjorn