Re: [PATCH V2 3/5] backlight: qcom-wled: Add support for short circuit handling
From: kgunda
Date: Wed May 09 2018 - 01:30:33 EST
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@xxxxxxxxxxxxxx>
---
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);
--
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