Re: [PATCH V4 7/8] backlight: qcom-wled: add support for short circuit handling

[kgunda@xxxxxxxxxxxxxx]

On 2018-07-20 19:37, Daniel Thompson wrote:
> On 09/07/18 11:22, 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>
> > Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> > ---
> > Changes from V3:
> > 	- Added Reviewed by tag.
> > 	- Addressed minor comments from Vinod
> >
> >   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 362d254..a14f1a6 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>
> > @@ -64,6 +67,16 @@
> >   #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)
> > @@ -113,17 +126,23 @@ 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);
> > @@ -174,6 +193,9 @@ static int wled_module_enable(struct wled *wled, 
> > int val)
> >   {
> >   	int rc;
> >   +	if (wled->disabled_by_short)
> > +		return -EFAULT;
>
> EFAULT means bad address (memory fault). Perhaps EIO or maybe even
> something more exotic like ENXIO might be more appropriate?
>
>
> > +
> >   	rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
> >   				WLED_CTRL_REG_MOD_EN,
> >   				WLED_CTRL_REG_MOD_EN_MASK,
> > @@ -210,18 +232,19 @@ 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;
> >   		}
> >   	}
> >   @@ -229,15 +252,61 @@ 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 = 0;
>
> Shouldn't this reset to 1 (e.g. we have just seen a short).
>
>
> Daniel.
Ok. I will change it in the next series.
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