Re: [PATCH V9 6/6] backlight: qcom-wled: Add auto string detection logic
From: Daniel Thompson
Date: Wed Oct 23 2019 - 11:43:53 EST
On Wed, Oct 23, 2019 at 12:37:03PM +0530, Kiran Gunda wrote:
> The auto string detection algorithm checks if the current WLED
> sink configuration is valid. It tries enabling every sink and
> checks if the OVP fault is observed. Based on this information
> it detects and enables the valid sink configuration.
> Auto calibration will be triggered when the OVP fault interrupts
> are seen frequently thereby it tries to fix the sink configuration.
>
> The auto-detection also kicks in when the connected LED string
> of the display-backlight malfunctions (because of damage) and
> requires the damaged string to be turned off to prevent the
> complete panel and/or board from being damaged.
>
> Signed-off-by: Kiran Gunda <kgunda@xxxxxxxxxxxxxx>
Reviewed-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
> ---
> drivers/video/backlight/qcom-wled.c | 400 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 394 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
> index 658b1e0..33b6007 100644
> --- a/drivers/video/backlight/qcom-wled.c
> +++ b/drivers/video/backlight/qcom-wled.c
> @@ -17,19 +17,29 @@
> #define WLED_MAX_STRINGS 4
>
> #define WLED_DEFAULT_BRIGHTNESS 2048
> -
> +#define WLED_SOFT_START_DLY_US 10000
> #define WLED3_SINK_REG_BRIGHT_MAX 0xFFF
>
> /* WLED3/WLED4 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_OVP_FAULT_STATUS BIT(1)
> +
> #define WLED3_CTRL_REG_MOD_EN 0x46
> #define WLED3_CTRL_REG_MOD_EN_MASK BIT(7)
> #define WLED3_CTRL_REG_MOD_EN_SHIFT 7
>
> +#define WLED3_CTRL_REG_FEEDBACK_CONTROL 0x48
> +
> #define WLED3_CTRL_REG_FREQ 0x4c
> #define WLED3_CTRL_REG_FREQ_MASK GENMASK(3, 0)
>
> #define WLED3_CTRL_REG_OVP 0x4d
> -#define WLED3_CTRL_REG_OVP_MASK GENMASK(1, 0)
> +#define WLED3_CTRL_REG_OVP_MASK GENMASK(1, 0)
>
> #define WLED3_CTRL_REG_ILIMIT 0x4e
> #define WLED3_CTRL_REG_ILIMIT_MASK GENMASK(2, 0)
> @@ -119,6 +129,7 @@ struct wled_config {
> bool ext_gen;
> bool cabc;
> bool external_pfet;
> + bool auto_detection_enabled;
> };
>
> struct wled {
> @@ -127,17 +138,22 @@ struct wled {
> struct regmap *regmap;
> struct mutex lock; /* Lock to avoid race from thread irq handler */
> ktime_t last_short_event;
> + ktime_t start_ovp_fault_time;
> u16 ctrl_addr;
> u16 sink_addr;
> u16 max_string_count;
> + u16 auto_detection_ovp_count;
> u32 brightness;
> u32 max_brightness;
> u32 short_count;
> + u32 auto_detect_count;
> bool disabled_by_short;
> bool has_short_detect;
> int short_irq;
> + int ovp_irq;
>
> struct wled_config cfg;
> + struct delayed_work ovp_work;
> int (*wled_set_brightness)(struct wled *wled, u16 brightness);
> };
>
> @@ -182,6 +198,13 @@ 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);
> + enable_irq(wled->ovp_irq);
> +}
> +
> static int wled_module_enable(struct wled *wled, int val)
> {
> int rc;
> @@ -193,7 +216,25 @@ static int wled_module_enable(struct wled *wled, int val)
> WLED3_CTRL_REG_MOD_EN,
> WLED3_CTRL_REG_MOD_EN_MASK,
> val << WLED3_CTRL_REG_MOD_EN_SHIFT);
> - return rc;
> + if (rc < 0)
> + return rc;
> +
> + if (wled->ovp_irq > 0) {
> + if (val) {
> + /*
> + * The hardware generates a storm of spurious OVP
> + * interrupts during soft start operations. So defer
> + * enabling the IRQ for 10ms to ensure that the
> + * soft start is complete.
> + */
> + schedule_delayed_work(&wled->ovp_work, HZ / 100);
> + } else {
> + if (!cancel_delayed_work_sync(&wled->ovp_work))
> + disable_irq(wled->ovp_irq);
> + }
> + }
> +
> + return 0;
> }
>
> static int wled_sync_toggle(struct wled *wled)
> @@ -300,6 +341,304 @@ static irqreturn_t wled_short_irq_handler(int irq, void *_wled)
> return IRQ_HANDLED;
> }
>
> +#define AUTO_DETECT_BRIGHTNESS 200
> +
> +static void wled_auto_string_detection(struct wled *wled)
> +{
> + int rc = 0, i;
> + u32 sink_config = 0, int_sts;
> + u8 sink_test = 0, sink_valid = 0, val;
> +
> + /* Read configured sink configuration */
> + rc = regmap_read(wled->regmap, wled->sink_addr +
> + WLED4_SINK_REG_CURR_SINK, &sink_config);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to read SINK configuration rc=%d\n",
> + rc);
> + goto failed_detect;
> + }
> +
> + /* Disable the module before starting detection */
> + rc = regmap_update_bits(wled->regmap,
> + wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN,
> + WLED3_CTRL_REG_MOD_EN_MASK, 0);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to disable WLED module rc=%d\n", rc);
> + goto failed_detect;
> + }
> +
> + /* Set low brightness across all sinks */
> + rc = wled4_set_brightness(wled, AUTO_DETECT_BRIGHTNESS);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to set brightness for auto detection rc=%d\n",
> + rc);
> + goto failed_detect;
> + }
> +
> + if (wled->cfg.cabc) {
> + for (i = 0; i < wled->cfg.num_strings; i++) {
> + rc = regmap_update_bits(wled->regmap, wled->sink_addr +
> + WLED4_SINK_REG_STR_CABC(i),
> + WLED4_SINK_REG_STR_CABC_MASK,
> + 0);
> + if (rc < 0)
> + goto failed_detect;
> + }
> + }
> +
> + /* Disable all sinks */
> + rc = regmap_write(wled->regmap,
> + wled->sink_addr + WLED4_SINK_REG_CURR_SINK, 0);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to disable all sinks rc=%d\n", rc);
> + goto failed_detect;
> + }
> +
> + /* Iterate through the strings one by one */
> + for (i = 0; i < wled->cfg.num_strings; i++) {
> + sink_test = BIT((WLED4_SINK_REG_CURR_SINK_SHFT + i));
> +
> + /* Enable feedback control */
> + rc = regmap_write(wled->regmap, wled->ctrl_addr +
> + WLED3_CTRL_REG_FEEDBACK_CONTROL, i + 1);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to enable feedback for SINK %d rc = %d\n",
> + i + 1, rc);
> + goto failed_detect;
> + }
> +
> + /* Enable the sink */
> + rc = regmap_write(wled->regmap, wled->sink_addr +
> + WLED4_SINK_REG_CURR_SINK, sink_test);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to configure SINK %d rc=%d\n",
> + i + 1, rc);
> + goto failed_detect;
> + }
> +
> + /* Enable the module */
> + rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
> + WLED3_CTRL_REG_MOD_EN,
> + WLED3_CTRL_REG_MOD_EN_MASK,
> + WLED3_CTRL_REG_MOD_EN_MASK);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to enable WLED module rc=%d\n",
> + rc);
> + goto failed_detect;
> + }
> +
> + usleep_range(WLED_SOFT_START_DLY_US,
> + WLED_SOFT_START_DLY_US + 1000);
> +
> + 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_CTRL_INT_RT_STS rc=%d\n",
> + rc);
> + goto failed_detect;
> + }
> +
> + if (int_sts & WLED3_CTRL_REG_OVP_FAULT_STATUS)
> + dev_dbg(wled->dev, "WLED OVP fault detected with SINK %d\n",
> + i + 1);
> + else
> + sink_valid |= sink_test;
> +
> + /* Disable the module */
> + rc = regmap_update_bits(wled->regmap,
> + wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN,
> + WLED3_CTRL_REG_MOD_EN_MASK, 0);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to disable WLED module rc=%d\n",
> + rc);
> + goto failed_detect;
> + }
> + }
> +
> + if (!sink_valid) {
> + dev_err(wled->dev, "No valid WLED sinks found\n");
> + wled->disabled_by_short = true;
> + goto failed_detect;
> + }
> +
> + if (sink_valid != sink_config) {
> + dev_warn(wled->dev, "%x is not a valid sink configuration - using %x instead\n",
> + sink_config, sink_valid);
> + sink_config = sink_valid;
> + }
> +
> + /* Write the new sink configuration */
> + rc = regmap_write(wled->regmap,
> + wled->sink_addr + WLED4_SINK_REG_CURR_SINK,
> + sink_config);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to reconfigure the default sink rc=%d\n",
> + rc);
> + goto failed_detect;
> + }
> +
> + /* Enable valid sinks */
> + for (i = 0; i < wled->cfg.num_strings; i++) {
> + if (wled->cfg.cabc) {
> + rc = regmap_update_bits(wled->regmap, wled->sink_addr +
> + WLED4_SINK_REG_STR_CABC(i),
> + WLED4_SINK_REG_STR_CABC_MASK,
> + WLED4_SINK_REG_STR_CABC_MASK);
> + if (rc < 0)
> + goto failed_detect;
> + }
> +
> + if (sink_config & BIT(WLED4_SINK_REG_CURR_SINK_SHFT + i))
> + val = WLED4_SINK_REG_STR_MOD_MASK;
> + else
> + val = 0x0; /* Disable modulator_en for unused sink */
> +
> + rc = regmap_write(wled->regmap, wled->sink_addr +
> + WLED4_SINK_REG_STR_MOD_EN(i), val);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to configure MODULATOR_EN rc=%d\n",
> + rc);
> + goto failed_detect;
> + }
> + }
> +
> + /* Restore the feedback setting */
> + rc = regmap_write(wled->regmap,
> + wled->ctrl_addr + WLED3_CTRL_REG_FEEDBACK_CONTROL, 0);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to restore feedback setting rc=%d\n",
> + rc);
> + goto failed_detect;
> + }
> +
> + /* Restore brightness */
> + rc = wled4_set_brightness(wled, wled->brightness);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to set brightness after auto detection rc=%d\n",
> + rc);
> + goto failed_detect;
> + }
> +
> + rc = regmap_update_bits(wled->regmap,
> + wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN,
> + WLED3_CTRL_REG_MOD_EN_MASK,
> + WLED3_CTRL_REG_MOD_EN_MASK);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to enable WLED module rc=%d\n", rc);
> + goto failed_detect;
> + }
> +
> +failed_detect:
> + return;
> +}
> +
> +#define WLED_AUTO_DETECT_OVP_COUNT 5
> +#define WLED_AUTO_DETECT_CNT_DLY_US USEC_PER_SEC
> +static bool wled_auto_detection_required(struct wled *wled)
> +{
> + s64 elapsed_time_us;
> +
> + if (!wled->cfg.auto_detection_enabled)
> + return false;
> +
> + /*
> + * Check if the OVP fault was an occasional one
> + * or if it's firing continuously, the latter qualifies
> + * for an auto-detection check.
> + */
> + if (!wled->auto_detection_ovp_count) {
> + wled->start_ovp_fault_time = ktime_get();
> + wled->auto_detection_ovp_count++;
> + } else {
> + elapsed_time_us = ktime_us_delta(ktime_get(),
> + wled->start_ovp_fault_time);
> + if (elapsed_time_us > WLED_AUTO_DETECT_CNT_DLY_US)
> + wled->auto_detection_ovp_count = 0;
> + else
> + wled->auto_detection_ovp_count++;
> +
> + if (wled->auto_detection_ovp_count >=
> + WLED_AUTO_DETECT_OVP_COUNT) {
> + wled->auto_detection_ovp_count = 0;
> + return true;
> + }
> + }
> +
> + return false;
> +}
> +
> +static int wled_auto_detection_at_init(struct wled *wled)
> +{
> + int rc;
> + u32 fault_status, rt_status;
> +
> + if (!wled->cfg.auto_detection_enabled)
> + return 0;
> +
> + rc = regmap_read(wled->regmap,
> + wled->ctrl_addr + WLED3_CTRL_REG_INT_RT_STS,
> + &rt_status);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to read RT status rc=%d\n", rc);
> + return rc;
> + }
> +
> + rc = regmap_read(wled->regmap,
> + wled->ctrl_addr + WLED3_CTRL_REG_FAULT_STATUS,
> + &fault_status);
> + if (rc < 0) {
> + dev_err(wled->dev, "Failed to read fault status rc=%d\n", rc);
> + return rc;
> + }
> +
> + if ((rt_status & WLED3_CTRL_REG_OVP_FAULT_STATUS) ||
> + (fault_status & WLED3_CTRL_REG_OVP_FAULT_BIT)) {
> + mutex_lock(&wled->lock);
> + wled_auto_string_detection(wled);
> + mutex_unlock(&wled->lock);
> + }
> +
> + return rc;
> +}
> +
> +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);
> +
> + if (fault_sts & WLED3_CTRL_REG_OVP_FAULT_BIT) {
> + if (wled_auto_detection_required(wled)) {
> + mutex_lock(&wled->lock);
> + wled_auto_string_detection(wled);
> + mutex_unlock(&wled->lock);
> + }
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> static int wled3_setup(struct wled *wled)
> {
> u16 addr;
> @@ -436,8 +775,10 @@ static int wled4_setup(struct wled *wled)
> sink_en |= 1 << temp;
> }
>
> - if (sink_cfg == sink_en)
> - return 0;
> + if (sink_cfg == sink_en) {
> + rc = wled_auto_detection_at_init(wled);
> + return rc;
> + }
>
> rc = regmap_update_bits(wled->regmap,
> wled->sink_addr + WLED4_SINK_REG_CURR_SINK,
> @@ -500,7 +841,9 @@ static int wled4_setup(struct wled *wled)
> return rc;
> }
>
> - return 0;
> + rc = wled_auto_detection_at_init(wled);
> +
> + return rc;
> }
>
> static const struct wled_config wled4_config_defaults = {
> @@ -511,6 +854,7 @@ static int wled4_setup(struct wled *wled)
> .switch_freq = 11,
> .cabc = false,
> .external_pfet = false,
> + .auto_detection_enabled = false,
> };
>
> static const u32 wled3_boost_i_limit_values[] = {
> @@ -677,6 +1021,7 @@ static int wled_configure(struct wled *wled, int version)
> { "qcom,ext-gen", &cfg->ext_gen, },
> { "qcom,cabc", &cfg->cabc, },
> { "qcom,external-pfet", &cfg->external_pfet, },
> + { "qcom,auto-string-detection", &cfg->auto_detection_enabled, },
> };
>
> prop_addr = of_get_address(dev->of_node, 0, NULL, NULL);
> @@ -797,6 +1142,40 @@ 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;
> + u32 val;
> +
> + wled->ovp_irq = platform_get_irq_byname(pdev, "ovp");
> + if (wled->ovp_irq < 0) {
> + dev_dbg(&pdev->dev, "OVP IRQ not found - disabling automatic string detection\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 = 0;
> + return 0;
> + }
> +
> + rc = regmap_read(wled->regmap, wled->ctrl_addr +
> + WLED3_CTRL_REG_MOD_EN, &val);
> + if (rc < 0)
> + return rc;
> +
> + /* Keep OVP irq disabled until module is enabled */
> + if (!(val & WLED3_CTRL_REG_MOD_EN_MASK))
> + disable_irq(wled->ovp_irq);
> +
> + return 0;
> +}
> +
> static const struct backlight_ops wled_ops = {
> .update_status = wled_update_status,
> };
> @@ -837,6 +1216,7 @@ static int wled_probe(struct platform_device *pdev)
>
> switch (version) {
> case 3:
> + wled->cfg.auto_detection_enabled = false;
> rc = wled3_setup(wled);
> if (rc) {
> dev_err(&pdev->dev, "wled3_setup failed\n");
> @@ -858,10 +1238,16 @@ static int wled_probe(struct platform_device *pdev)
> break;
> }
>
> + INIT_DELAYED_WORK(&wled->ovp_work, wled_ovp_work);
> +
> rc = wled_configure_short_irq(wled, pdev);
> if (rc < 0)
> return rc;
>
> + rc = wled_configure_ovp_irq(wled, pdev);
> + if (rc < 0)
> + return rc;
> +
> val = WLED_DEFAULT_BRIGHTNESS;
> of_property_read_u32(pdev->dev.of_node, "default-brightness", &val);
>
> @@ -880,7 +1266,9 @@ static int wled_remove(struct platform_device *pdev)
> struct wled *wled = dev_get_drvdata(&pdev->dev);
>
> mutex_destroy(&wled->lock);
> + cancel_delayed_work_sync(&wled->ovp_work);
> disable_irq(wled->short_irq);
> + disable_irq(wled->ovp_irq);
>
> return 0;
> }
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>