On 2018-05-08 16:05, Daniel Thompson wrote:

On Thu, May 03, 2018 at 03:42:30PM +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

drivers/video/backlight/qcom-wled.c | 134 ++++++++++++++++++++++++++++++++++-- 1 file changed, 130 insertions(+), 4 deletions(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c index be8b8d3..2cfba77 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -10,6 +10,9 @@

• GNU General Public License for more details.

*/

+#include <linux/delay.h> +#include <linux/interrupt.h> +#include <linux/ktime.h> #include <linux/kernel.h> #include <linux/backlight.h> #include <linux/module.h> @@ -23,7 +26,9 @@

#define WLED3_SINK_REG_BRIGHT_MAX 0xFFF

-/* Control registers */ +/* WLED3 Control registers */ +#define WLED3_CTRL_REG_FAULT_STATUS 0x08

#define WLED3_CTRL_REG_MOD_EN 0x46 #define WLED3_CTRL_REG_MOD_EN_MASK BIT(7)

@@ -36,7 +41,17 @@ #define WLED3_CTRL_REG_ILIMIT 0x4e #define WLED3_CTRL_REG_ILIMIT_MASK GENMASK(2, 0)

-/* sink registers */ +/* WLED4 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

+/* WLED3 sink registers */ #define WLED3_SINK_REG_SYNC 0x47 #define WLED3_SINK_REG_SYNC_MASK GENMASK(2, 0) #define WLED4_SINK_REG_SYNC_MASK GENMASK(3, 0) @@ -130,17 +145,23 @@ 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 ISR */

• ktime_t last_short_event; u16 ctrl_addr; u16 sink_addr; u32 brightness; u32 max_brightness;

• u32 short_count; const int *version;

• int short_irq;

• bool force_mod_disable;

  struct wled_config cfg; int (*wled_set_brightness)(struct wled *wled, u16 brightness);

@@ -192,6 +213,9 @@ static int wled_module_enable(struct wled *wled, int val) { int rc;

• if (wled->force_mod_disable)

• return 0;
  

• rc = regmap_update_bits(wled->regmap, wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN, WLED3_CTRL_REG_MOD_EN_MASK,

@@ -248,12 +272,13 @@ 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->wled_sync_toggle(wled);

@@ -267,15 +292,60 @@ 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 HZ

So we think a short report every quarter second is harmless?

Yes. We wait for the short to report 5 times with in this time. If the short still persists, we go and disable the WLED module to avoid the damage. This is suggested by the HW team.

...

+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 = 0;
  

• if (wled->short_count > WLED_SHORT_CNT_MAX) {

• dev_err(wled->dev, "Short trigged %d times, disabling WLED 
  

forever!\n",

• 	wled->short_count);
  

• wled->force_mod_disable = 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; @@ -435,6 +505,21 @@ static int wled4_setup(struct wled *wled) 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;
  

• }
• return 0;

}

@@ -446,6 +531,7 @@ static int wled4_setup(struct wled *wled) .switch_freq = 11, .enabled_strings = 0xf, .cabc = false,

• .external_pfet = true,

};

static const u32 wled3_boost_i_limit_values[] = { @@ -628,6 +714,7 @@ static int wled_configure(struct wled *wled) { "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);

@@ -701,6 +788,39 @@ static int wled_configure(struct wled *wled) return 0; }

+static int wled_configure_short_irq(struct wled *wled,

• 		    struct platform_device *pdev)
  

+{

• int rc = 0;
• /* PM8941 doesn't have the short detection support */
• if (*wled->version == WLED_PM8941)

• 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;
  

• wled->short_irq = platform_get_irq_byname(pdev, "short");
• if (wled->short_irq < 0) {

• dev_dbg(&pdev->dev, "short irq is not used\n");
  

• return 0;
  

• }
• rc = devm_request_threaded_irq(wled->dev, wled->short_irq,

• 		       NULL, wled_short_irq_handler,
  

NULL? There's no register we can check to make sure the interrupt handler did not enter spuriously?

There is FAULT_STATUS register. I will address it in the next series.

...

• 		       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, }; @@ -733,6 +853,8 @@ static int wled_probe(struct platform_device *pdev) return -ENODEV; }

• mutex_init(&wled->lock);
• rc = wled_configure(wled); if (rc) return rc;

@@ -752,6 +874,10 @@ static int wled_probe(struct platform_device *pdev) } }

• 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