linux-kernel - Re: [PATCH V1 3/4] qcom: spmi-wled: Add support for OVP interrupt handling

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Date:   Mon, 4 Dec 2017 20:45:23 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Kiran Gunda <kgunda@...eaurora.org>
Cc:     linux-arm-msm@...r.kernel.org, Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Richard Purdie <rpurdie@...ys.net>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH V1 3/4] qcom: spmi-wled: Add support for OVP interrupt
 handling

On Thu 16 Nov 04:18 PST 2017, 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@...eaurora.org>
> ---
>  .../bindings/leds/backlight/qcom-spmi-wled.txt     |  7 +-
>  drivers/video/backlight/qcom-spmi-wled.c           | 83 ++++++++++++++++++++++
>  2 files changed, 87 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/leds/backlight/qcom-spmi-wled.txt b/Documentation/devicetree/bindings/leds/backlight/qcom-spmi-wled.txt
> index 768608c..d39ee93 100644
> --- a/Documentation/devicetree/bindings/leds/backlight/qcom-spmi-wled.txt
> +++ b/Documentation/devicetree/bindings/leds/backlight/qcom-spmi-wled.txt
> @@ -92,7 +92,7 @@ The PMIC is connected to the host processor via SPMI bus.
>  	Usage:      optional
>  	Value type: <string>
>  	Definition: Interrupt names associated with the interrupts.
> -		    Must be "sc-irq".
> +		    Currently supported interrupts are "sc-irq" and "ovp-irq".
>  

As before, we know this is an IRQ, so omit the -irq from the name.

[..]
> diff --git a/drivers/video/backlight/qcom-spmi-wled.c b/drivers/video/backlight/qcom-spmi-wled.c
[..]
> @@ -115,6 +123,28 @@ static int qcom_wled_module_enable(struct qcom_wled *wled, int val)
>  	rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
>  			QCOM_WLED_CTRL_MOD_ENABLE, QCOM_WLED_CTRL_MOD_EN_MASK,
>  			val << QCOM_WLED_CTRL_MODULE_EN_SHIFT);
> +	if (rc < 0)
> +		return rc;
> +	/*
> +	 * Wait for at least 10ms before enabling OVP fault interrupt after
> +	 * enabling the module so that soft start is completed. Keep the OVP
> +	 * interrupt disabled when the module is disabled.
> +	 */
> +	if (val) {
> +		usleep_range(QCOM_WLED_SOFT_START_DLY_US,
> +				QCOM_WLED_SOFT_START_DLY_US + 1000);

This is sleeping in the brightness/enable code path, can you
schedule_delayed_work() instead to not block this code path
unnecessarily?

> +
> +		if (wled->cfg.ovp_irq > 0 && wled->ovp_irq_disabled) {
> +			enable_irq(wled->cfg.ovp_irq);
> +			wled->ovp_irq_disabled = false;
> +		}
> +	} else {
> +		if (wled->cfg.ovp_irq > 0 && !wled->ovp_irq_disabled) {
> +			disable_irq(wled->cfg.ovp_irq);
> +			wled->ovp_irq_disabled = true;
> +		}
> +	}
> +
>  	return rc;
>  }
>  
> @@ -264,12 +294,42 @@ static irqreturn_t qcom_wled_sc_irq_handler(int irq, void *_wled)
>  	return IRQ_HANDLED;
>  }
>  
> +static irqreturn_t qcom_wled_ovp_irq_handler(int irq, void *_wled)
> +{
> +	struct qcom_wled *wled = _wled;
> +	int rc;
> +	u32 int_sts, fault_sts;
> +
> +	rc = regmap_read(wled->regmap,
> +			wled->ctrl_addr + QCOM_WLED_CTRL_INT_RT_STS, &int_sts);
> +	if (rc < 0) {
> +		pr_err("Error in reading WLED_INT_RT_STS rc=%d\n", rc);
> +		return IRQ_HANDLED;
> +	}
> +
> +	rc = regmap_read(wled->regmap, wled->ctrl_addr +
> +			QCOM_WLED_CTRL_FAULT_STATUS, &fault_sts);
> +	if (rc < 0) {
> +		pr_err("Error in reading WLED_FAULT_STATUS rc=%d\n", rc);
> +		return IRQ_HANDLED;
> +	}
> +
> +	if (fault_sts &
> +		(QCOM_WLED_CTRL_OVP_FAULT_BIT | QCOM_WLED_CTRL_ILIM_FAULT_BIT))
> +		pr_err("WLED OVP fault detected, int_sts=%x fault_sts= %x\n",
> +			int_sts, fault_sts);

All this function does is print things to the log. When is this
information consumed and by whom? dev_dbg() instead?

> +
> +	return IRQ_HANDLED;
> +}
> +
>  static int qcom_wled_setup(struct qcom_wled *wled)
>  {
>  	int rc, temp, i;
>  	u8 sink_en = 0;
> +	u32 val;
>  	u8 string_cfg = wled->cfg.string_cfg;
>  	int sc_irq = wled->cfg.sc_irq;
> +	int ovp_irq = wled->cfg.ovp_irq;
>  
>  	rc = regmap_update_bits(wled->regmap,
>  			wled->ctrl_addr + QCOM_WLED_CTRL_OVP,
> @@ -367,6 +427,25 @@ static int qcom_wled_setup(struct qcom_wled *wled)
>  		}
>  	}
>  
> +	if (ovp_irq >= 0) {

As with the previous patch.

[..]
> @@ -539,6 +618,10 @@ static int qcom_wled_configure(struct qcom_wled *wled, struct device *dev)
[..]
> +	wled->cfg.ovp_irq = platform_get_irq_byname(wled->pdev, "ovp-irq");
> +	if (wled->cfg.ovp_irq < 0)
> +		dev_dbg(&wled->pdev->dev, "ovp irq is not used\n");
> +

Regards,
Bjorn