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Date:   Thu, 17 Oct 2019 18:00:01 +0530
From:   kgunda@codeaurora.org
To:     Daniel Thompson <daniel.thompson@linaro.org>
Cc:     bjorn.andersson@linaro.org, jingoohan1@gmail.com,
        lee.jones@linaro.org, b.zolnierkie@samsung.com,
        dri-devel@lists.freedesktop.org, jacek.anaszewski@gmail.com,
        pavel@ucw.cz, robh+dt@kernel.org, mark.rutland@arm.com,
        linux-leds@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, Andy Gross <agross@kernel.org>,
        linux-arm-msm@vger.kernel.org, linux-fbdev@vger.kernel.org
Subject: Re: [PATCH V7 5/6] backlight: qcom-wled: add support for short
 circuit handling.
In-Reply-To: <20191017110945.6dbldlrykumvlpqm@holly.lan>
References: <1571220826-7740-1-git-send-email-kgunda@codeaurora.org>
 <1571220826-7740-6-git-send-email-kgunda@codeaurora.org>
 <20191017110945.6dbldlrykumvlpqm@holly.lan>
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On 2019-10-17 16:39, Daniel Thompson wrote:
> On Wed, Oct 16, 2019 at 03:43:45PM +0530, Kiran Gunda wrote:
>> Handle the short circuit interrupt and check if the short circuit
>> interrupt is valid. Re-enable the module to check if it goes
>> away. Disable the module altogether if the short circuit event
>> persists.
>> 
>> Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
>> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> 
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> 
Thanks for that !
>> ---
>>  drivers/video/backlight/qcom-wled.c | 132 
>> ++++++++++++++++++++++++++++++++++--
>>  1 file changed, 128 insertions(+), 4 deletions(-)
>> 
>> diff --git a/drivers/video/backlight/qcom-wled.c 
>> b/drivers/video/backlight/qcom-wled.c
>> index 2807b4b..b5b125c 100644
>> --- a/drivers/video/backlight/qcom-wled.c
>> +++ b/drivers/video/backlight/qcom-wled.c
>> @@ -2,6 +2,9 @@
>>  /* Copyright (c) 2015, Sony Mobile Communications, AB.
>>   */
>> 
>> +#include <linux/delay.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/ktime.h>
>>  #include <linux/kernel.h>
>>  #include <linux/backlight.h>
>>  #include <linux/module.h>
>> @@ -56,6 +59,16 @@
>>  #define WLED3_SINK_REG_STR_CABC(n)			(0x66 + (n * 0x10))
>>  #define  WLED3_SINK_REG_STR_CABC_MASK			BIT(7)
>> 
>> +/* WLED4 specific control registers */
>> +#define WLED4_CTRL_REG_SHORT_PROTECT			0x5e
>> +#define  WLED4_CTRL_REG_SHORT_EN_MASK			BIT(7)
>> +
>> +#define WLED4_CTRL_REG_SEC_ACCESS			0xd0
>> +#define  WLED4_CTRL_REG_SEC_UNLOCK			0xa5
>> +
>> +#define WLED4_CTRL_REG_TEST1				0xe2
>> +#define  WLED4_CTRL_REG_TEST1_EXT_FET_DTEST2		0x09
>> +
>>  /* WLED4 specific sink registers */
>>  #define WLED4_SINK_REG_CURR_SINK			0x46
>>  #define  WLED4_SINK_REG_CURR_SINK_MASK			GENMASK(7, 4)
>> @@ -105,17 +118,23 @@ struct wled_config {
>>  	bool cs_out_en;
>>  	bool ext_gen;
>>  	bool cabc;
>> +	bool external_pfet;
>>  };
>> 
>>  struct wled {
>>  	const char *name;
>>  	struct device *dev;
>>  	struct regmap *regmap;
>> +	struct mutex lock;	/* Lock to avoid race from thread irq handler */
>> +	ktime_t last_short_event;
>>  	u16 ctrl_addr;
>>  	u16 sink_addr;
>>  	u16 max_string_count;
>>  	u32 brightness;
>>  	u32 max_brightness;
>> +	u32 short_count;
>> +	bool disabled_by_short;
>> +	bool has_short_detect;
>> 
>>  	struct wled_config cfg;
>>  	int (*wled_set_brightness)(struct wled *wled, u16 brightness);
>> @@ -166,6 +185,9 @@ static int wled_module_enable(struct wled *wled, 
>> int val)
>>  {
>>  	int rc;
>> 
>> +	if (wled->disabled_by_short)
>> +		return -ENXIO;
>> +
>>  	rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
>>  				WLED3_CTRL_REG_MOD_EN,
>>  				WLED3_CTRL_REG_MOD_EN_MASK,
>> @@ -202,18 +224,19 @@ static int wled_update_status(struct 
>> backlight_device *bl)
>>  	    bl->props.state & BL_CORE_FBBLANK)
>>  		brightness = 0;
>> 
>> +	mutex_lock(&wled->lock);
>>  	if (brightness) {
>>  		rc = wled->wled_set_brightness(wled, brightness);
>>  		if (rc < 0) {
>>  			dev_err(wled->dev, "wled failed to set brightness rc:%d\n",
>>  				rc);
>> -			return rc;
>> +			goto unlock_mutex;
>>  		}
>> 
>>  		rc = wled_sync_toggle(wled);
>>  		if (rc < 0) {
>>  			dev_err(wled->dev, "wled sync failed rc:%d\n", rc);
>> -			return rc;
>> +			goto unlock_mutex;
>>  		}
>>  	}
>> 
>> @@ -221,15 +244,61 @@ static int wled_update_status(struct 
>> backlight_device *bl)
>>  		rc = wled_module_enable(wled, !!brightness);
>>  		if (rc < 0) {
>>  			dev_err(wled->dev, "wled enable failed rc:%d\n", rc);
>> -			return rc;
>> +			goto unlock_mutex;
>>  		}
>>  	}
>> 
>>  	wled->brightness = brightness;
>> 
>> +unlock_mutex:
>> +	mutex_unlock(&wled->lock);
>> +
>>  	return rc;
>>  }
>> 
>> +#define WLED_SHORT_DLY_MS			20
>> +#define WLED_SHORT_CNT_MAX			5
>> +#define WLED_SHORT_RESET_CNT_DLY_US		USEC_PER_SEC
>> +
>> +static irqreturn_t wled_short_irq_handler(int irq, void *_wled)
>> +{
>> +	struct wled *wled = _wled;
>> +	int rc;
>> +	s64 elapsed_time;
>> +
>> +	wled->short_count++;
>> +	mutex_lock(&wled->lock);
>> +	rc = wled_module_enable(wled, false);
>> +	if (rc < 0) {
>> +		dev_err(wled->dev, "wled disable failed rc:%d\n", rc);
>> +		goto unlock_mutex;
>> +	}
>> +
>> +	elapsed_time = ktime_us_delta(ktime_get(),
>> +				      wled->last_short_event);
>> +	if (elapsed_time > WLED_SHORT_RESET_CNT_DLY_US)
>> +		wled->short_count = 1;
>> +
>> +	if (wled->short_count > WLED_SHORT_CNT_MAX) {
>> +		dev_err(wled->dev, "Short trigged %d times, disabling WLED 
>> forever!\n",
>> +			wled->short_count);
>> +		wled->disabled_by_short = true;
>> +		goto unlock_mutex;
>> +	}
>> +
>> +	wled->last_short_event = ktime_get();
>> +
>> +	msleep(WLED_SHORT_DLY_MS);
>> +	rc = wled_module_enable(wled, true);
>> +	if (rc < 0)
>> +		dev_err(wled->dev, "wled enable failed rc:%d\n", rc);
>> +
>> +unlock_mutex:
>> +	mutex_unlock(&wled->lock);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>>  static int wled3_setup(struct wled *wled)
>>  {
>>  	u16 addr;
>> @@ -318,7 +387,7 @@ static int wled4_setup(struct wled *wled)
>>  	int rc, temp, i, j;
>>  	u16 addr;
>>  	u8 sink_en = 0;
>> -	u32 sink_cfg = 0;
>> +	u32 sink_cfg;
>> 
>>  	rc = regmap_update_bits(wled->regmap,
>>  				wled->ctrl_addr + WLED3_CTRL_REG_OVP,
>> @@ -340,6 +409,21 @@ static int wled4_setup(struct wled *wled)
>>  	if (rc < 0)
>>  		return rc;
>> 
>> +	if (wled->cfg.external_pfet) {
>> +		/* Unlock the secure register access */
>> +		rc = regmap_write(wled->regmap, wled->ctrl_addr +
>> +				  WLED4_CTRL_REG_SEC_ACCESS,
>> +				  WLED4_CTRL_REG_SEC_UNLOCK);
>> +		if (rc < 0)
>> +			return rc;
>> +
>> +		rc = regmap_write(wled->regmap,
>> +				  wled->ctrl_addr + WLED4_CTRL_REG_TEST1,
>> +				  WLED4_CTRL_REG_TEST1_EXT_FET_DTEST2);
>> +		if (rc < 0)
>> +			return rc;
>> +	}
>> +
>>  	rc = regmap_read(wled->regmap, wled->sink_addr +
>>  			 WLED4_SINK_REG_CURR_SINK, &sink_cfg);
>>  	if (rc < 0)
>> @@ -425,6 +509,7 @@ static int wled4_setup(struct wled *wled)
>>  	.num_strings = 4,
>>  	.switch_freq = 11,
>>  	.cabc = false,
>> +	.external_pfet = false,
>>  };
>> 
>>  static const u32 wled3_boost_i_limit_values[] = {
>> @@ -590,6 +675,7 @@ static int wled_configure(struct wled *wled, int 
>> version)
>>  		{ "qcom,cs-out", &cfg->cs_out_en, },
>>  		{ "qcom,ext-gen", &cfg->ext_gen, },
>>  		{ "qcom,cabc", &cfg->cabc, },
>> +		{ "qcom,external-pfet", &cfg->external_pfet, },
>>  	};
>> 
>>  	prop_addr = of_get_address(dev->of_node, 0, NULL, NULL);
>> @@ -678,6 +764,38 @@ static int wled_configure(struct wled *wled, int 
>> version)
>>  	return 0;
>>  }
>> 
>> +static int wled_configure_short_irq(struct wled *wled,
>> +				    struct platform_device *pdev)
>> +{
>> +	int rc, short_irq;
>> +
>> +	if (!wled->has_short_detect)
>> +		return 0;
>> +
>> +	rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
>> +				WLED4_CTRL_REG_SHORT_PROTECT,
>> +				WLED4_CTRL_REG_SHORT_EN_MASK,
>> +				WLED4_CTRL_REG_SHORT_EN_MASK);
>> +	if (rc < 0)
>> +		return rc;
>> +
>> +	short_irq = platform_get_irq_byname(pdev, "short");
>> +	if (short_irq < 0) {
>> +		dev_dbg(&pdev->dev, "short irq is not used\n");
>> +		return 0;
>> +	}
>> +
>> +	rc = devm_request_threaded_irq(wled->dev, short_irq,
>> +				       NULL, wled_short_irq_handler,
>> +				       IRQF_ONESHOT,
>> +				       "wled_short_irq", wled);
>> +	if (rc < 0)
>> +		dev_err(wled->dev, "Unable to request short_irq (err:%d)\n",
>> +			rc);
>> +
>> +	return rc;
>> +}
>> +
>>  static const struct backlight_ops wled_ops = {
>>  	.update_status = wled_update_status,
>>  };
>> @@ -711,6 +829,7 @@ static int wled_probe(struct platform_device 
>> *pdev)
>>  		return -ENODEV;
>>  	}
>> 
>> +	mutex_init(&wled->lock);
>>  	rc = wled_configure(wled, version);
>>  	if (rc)
>>  		return rc;
>> @@ -725,6 +844,7 @@ static int wled_probe(struct platform_device 
>> *pdev)
>>  		break;
>> 
>>  	case 4:
>> +		wled->has_short_detect = true;
>>  		rc = wled4_setup(wled);
>>  		if (rc) {
>>  			dev_err(&pdev->dev, "wled4_setup failed\n");
>> @@ -737,6 +857,10 @@ static int wled_probe(struct platform_device 
>> *pdev)
>>  		break;
>>  	}
>> 
>> +	rc = wled_configure_short_irq(wled, pdev);
>> +	if (rc < 0)
>> +		return rc;
>> +
>>  	val = WLED_DEFAULT_BRIGHTNESS;
>>  	of_property_read_u32(pdev->dev.of_node, "default-brightness", &val);
>> 
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>>  a Linux Foundation Collaborative Project
>>