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    SubjectRe: [PATCH V7 5/6] backlight: qcom-wled: add support for short circuit handling.
    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>

    > ---
    > 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
    >

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