Re: [PATCH V1 4/5] backlight: qcom-wled: Add support for OVP interrupt handling

[Bjorn Andersson]

On Thu 03 May 02:57 PDT 2018, Kiran Gunda wrote:

> WLED peripheral has over voltage protection(OVP) circuitry and the OVP
> fault is notified through an interrupt. Though this fault condition rising
> is due to an incorrect hardware configuration is mitigated in the hardware,
> it still needs to be detected and handled. Add support for it.
> 
> When WLED module is enabled, keep OVP fault interrupt disabled for 10 ms to
> account for soft start delay.
> 
> Signed-off-by: Kiran Gunda <kgunda@xxxxxxxxxxxxxx>
> ---
>  drivers/video/backlight/qcom-wled.c | 118 +++++++++++++++++++++++++++++++++++-
>  1 file changed, 116 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
> index 2cfba77..80ae084 100644
> --- a/drivers/video/backlight/qcom-wled.c
> +++ b/drivers/video/backlight/qcom-wled.c
> @@ -23,14 +23,20 @@
>  
>  /* From DT binding */
>  #define WLED_DEFAULT_BRIGHTNESS				2048
> -
> +#define WLED_SOFT_START_DLY_US				10000
>  #define WLED3_SINK_REG_BRIGHT_MAX			0xFFF
>  
>  /* WLED3 Control registers */
>  #define WLED3_CTRL_REG_FAULT_STATUS			0x08
> +#define  WLED3_CTRL_REG_ILIM_FAULT_BIT			BIT(0)
> +#define  WLED3_CTRL_REG_OVP_FAULT_BIT			BIT(1)
> +#define  WLED4_CTRL_REG_SC_FAULT_BIT			BIT(2)
> +
> +#define WLED3_CTRL_REG_INT_RT_STS			0x10
>  
>  #define WLED3_CTRL_REG_MOD_EN				0x46
>  #define  WLED3_CTRL_REG_MOD_EN_MASK			BIT(7)
> +#define  WLED3_CTRL_REG_MOD_EN_BIT			BIT(7)

"BIT(7)" is not a "bit" it's a "mask", so perhaps you could use the
define with that name...which has the same value?

>  
>  #define WLED3_CTRL_REG_FREQ				0x4c
>  #define  WLED3_CTRL_REG_FREQ_MASK			GENMASK(3, 0)
> @@ -161,9 +167,12 @@ struct wled {
>  	u32 short_count;
>  	const int *version;
>  	int short_irq;
> +	int ovp_irq;
>  	bool force_mod_disable;
> +	bool ovp_irq_disabled;
>  
>  	struct wled_config cfg;
> +	struct delayed_work ovp_work;
>  	int (*wled_set_brightness)(struct wled *wled, u16 brightness);
>  	int (*wled_sync_toggle)(struct wled *wled);
>  };
> @@ -209,6 +218,32 @@ static int wled4_set_brightness(struct wled *wled, u16 brightness)
>  	return 0;
>  }
>  
> +static void wled_ovp_work(struct work_struct *work)
> +{
> +	u32 val;
> +	int rc;
> +
> +	struct wled *wled = container_of(work,
> +					 struct wled, ovp_work.work);
> +
> +	rc = regmap_read(wled->regmap, wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN,
> +			 &val);
> +	if (rc < 0)
> +		return;
> +
> +	if (val & WLED3_CTRL_REG_MOD_EN_BIT) {
> +		if (wled->ovp_irq > 0 && wled->ovp_irq_disabled) {
> +			enable_irq(wled->ovp_irq);
> +			wled->ovp_irq_disabled = false;
> +		}
> +	} else {
> +		if (wled->ovp_irq > 0 && !wled->ovp_irq_disabled) {
> +			disable_irq(wled->ovp_irq);
> +			wled->ovp_irq_disabled = true;
> +		}
> +	}
> +}
> +
>  static int wled_module_enable(struct wled *wled, int val)
>  {
>  	int rc;
> @@ -220,7 +255,12 @@ static int wled_module_enable(struct wled *wled, int val)
>  				WLED3_CTRL_REG_MOD_EN,
>  				WLED3_CTRL_REG_MOD_EN_MASK,
>  				WLED3_CTRL_REG_MOD_EN_MASK);
> -	return rc;
> +	if (rc < 0)
> +		return rc;
> +
> +	schedule_delayed_work(&wled->ovp_work, WLED_SOFT_START_DLY_US);

Do you really want to delay the work on disable?

Wouldn't it be better to use a delay worker for the enablement and in
the disable case you cancel the work and just disable_irq() directly
here.

But more importantly, if this is only related to auto detection, do you
really want to enable/disable the ovp_irq after you have detected the
string configuration?

> +
> +	return 0;
>  }
>  
>  static int wled3_sync_toggle(struct wled *wled)
> @@ -346,6 +386,36 @@ static irqreturn_t wled_short_irq_handler(int irq, void *_wled)
>  	return IRQ_HANDLED;
>  }
>  
> +static irqreturn_t wled_ovp_irq_handler(int irq, void *_wled)
> +{
> +	struct wled *wled = _wled;
> +	int rc;
> +	u32 int_sts, fault_sts;
> +
> +	rc = regmap_read(wled->regmap,
> +			 wled->ctrl_addr + WLED3_CTRL_REG_INT_RT_STS, &int_sts);
> +	if (rc < 0) {
> +		dev_err(wled->dev, "Error in reading WLED3_INT_RT_STS rc=%d\n",
> +			rc);
> +		return IRQ_HANDLED;
> +	}
> +
> +	rc = regmap_read(wled->regmap, wled->ctrl_addr +
> +			 WLED3_CTRL_REG_FAULT_STATUS, &fault_sts);
> +	if (rc < 0) {
> +		dev_err(wled->dev, "Error in reading WLED_FAULT_STATUS rc=%d\n",
> +			rc);
> +		return IRQ_HANDLED;
> +	}
> +
> +	if (fault_sts &
> +		(WLED3_CTRL_REG_OVP_FAULT_BIT | WLED3_CTRL_REG_ILIM_FAULT_BIT))
> +		dev_dbg(wled->dev, "WLED OVP fault detected, int_sts=%x fault_sts= %x\n",
> +			int_sts, fault_sts);
> +

It's hard to give a good review on this, as the actual logic comes in
the next patch. And as these two patches both implement auto detection
(without a clear separation) I think you should squash them.

> +	return IRQ_HANDLED;
> +}
> +
>  static int wled3_setup(struct wled *wled)
>  {
>  	u16 addr;
> @@ -821,6 +891,44 @@ static int wled_configure_short_irq(struct wled *wled,
>  	return rc;
>  }
>  
> +static int wled_configure_ovp_irq(struct wled *wled,
> +				  struct platform_device *pdev)
> +{
> +	int rc = 0;
> +	u32 val;
> +
> +	if (*wled->version == WLED_PM8941)
> +		return 0;
> +
> +	wled->ovp_irq = platform_get_irq_byname(pdev, "ovp");
> +	if (wled->ovp_irq < 0) {
> +		dev_dbg(&pdev->dev, "ovp irq is not used\n");
> +		return 0;
> +	}
> +
> +	rc = devm_request_threaded_irq(wled->dev, wled->ovp_irq, NULL,
> +				       wled_ovp_irq_handler, IRQF_ONESHOT,
> +				       "wled_ovp_irq", wled);
> +	if (rc < 0) {
> +		dev_err(wled->dev, "Unable to request ovp_irq (err:%d)\n",
> +			rc);

wled->ovp_irq might be > 0 here which means wled_ovp_work() will find it
valid and call enabled_irq()/disable_irq() on it.

> +		return 0;
> +	}
> +

Regards,
Bjorn