leds: bcm6328: Handle default-state of LEDs correctly

The default-state handler assumes that the LED is active low and omits use of the shift macro causing "keep" to misdetect the state.

Determine the brightness and then use the led set function to apply it.

Update the documentation to indicate that this driver works for the BCM63168 (which has many active high LEDs) too.

Signed-off-by Simon Arlott <[email protected]>

---
  .../devicetree/bindings/leds/leds-bcm6328.txt      |  2 +-
  drivers/leds/leds-bcm6328.c                        | 23 ++++++++++++----------
  2 files changed, 14 insertions(+), 11 deletions(-)

Documentation/devicetree/bindings/leds/leds-bcm6328.txt +0 -0

index f9e36ad..d00260d 100644

drivers/leds/leds-bcm6328.c +13 -10

index 1793727..771c171 100644
@@ -259,7 +259,6 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  		       unsigned long *blink_leds, unsigned long *blink_delay)
  {
  	struct bcm6328_led *led;
-	unsigned long flags;
  	const char *state;
  	int rc;
 

@@ -282,13 +281,12 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  						    NULL);
 
  	if (!of_property_read_string(nc, "default-state", &state)) {
-		spin_lock_irqsave(lock, flags);
  		if (!strcmp(state, "on")) {
  			led->cdev.brightness = LED_FULL;
-			bcm6328_led_mode(led, BCM6328_LED_MODE_ON);
  		} else if (!strcmp(state, "keep")) {
  			void __iomem *mode;
  			unsigned long val, shift;
+			unsigned long flags;
 
  			shift = bcm6328_pin2shift(led->pin);
  			if (shift / 16)

@@ -296,19 +294,24 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  			else
  				mode = mem + BCM6328_REG_MODE_LO;
 
-			val = bcm6328_led_read(mode) >> (shift % 16);
+			spin_lock_irqsave(lock, flags);
+			val = bcm6328_led_read(mode);
+			spin_unlock_irqrestore(lock, flags);
+
+			val >>= BCM6328_LED_SHIFT(shift % 16);
  			val &= BCM6328_LED_MODE_MASK;
-			if (val == BCM6328_LED_MODE_ON)
+
+			dev_info(dev, "pin %lu = %08lx\n", led->pin, val);
+			if ((led->active_low && val == BCM6328_LED_MODE_ON) ||
+			    (!led->active_low && val == BCM6328_LED_MODE_OFF))
  				led->cdev.brightness = LED_FULL;
-			else {
+			else
  				led->cdev.brightness = LED_OFF;
-				bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
-			}
  		} else {
  			led->cdev.brightness = LED_OFF;
-			bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
  		}
-		spin_unlock_irqrestore(lock, flags);
+
+		bcm6328_led_set(&led->cdev, led->cdev.brightness);
  	}
 
  	led->cdev.brightness_set = bcm6328_led_set;

Hi Simon,

Thanks for the patch. There are conflicts when applying it to the LED tree:

git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds.git

Please use it as a code base for your LED development.

Quoted 5 lines · Jacek Anaszewski

Hi Simon,

Thanks for the patch. There are conflicts when applying it to the LED tree:

Quoted 3 lines

git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds.git

Please use it as a code base for your LED development.

This has already been fixed in the devel branch by d19e6b6a0062c86a75365f0715fd079245f6aab9, although I think bcm6328_led() should adjust its use of the spinlock
to only cover reading the register and call bcm6328_led_set() instead
of copying the code from it.

When ensuring a consistent initial LED state in bcm6328_led (as they may be blinking instead of on/off), the LED register is set using a copy of bcm6328_led_set(). To avoid further errors relating to active low handling, call this function directly instead.

As bcm6328_led_set() expects to acquire the spinlock, narrow the locking to only cover reading of the current state. There is no need to hold the spinlock between reading the current value and setting it again because the LED device has not yet been registered.

Signed-off-by Simon Arlott <[email protected]>

---
  drivers/leds/leds-bcm6328.c | 14 +++++---------
  1 file changed, 5 insertions(+), 9 deletions(-)

drivers/leds/leds-bcm6328.c +4 -3

index c7ea5c6..db327bd 100644
@@ -264,7 +264,6 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  		       unsigned long *blink_leds, unsigned long *blink_delay)
  {
  	struct bcm6328_led *led;
-	unsigned long flags;
  	const char *state;
  	int rc;
 

@@ -286,13 +285,12 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  						    "linux,default-trigger",
  						    NULL);
 
-	spin_lock_irqsave(lock, flags);
  	if (!of_property_read_string(nc, "default-state", &state)) {
  		if (!strcmp(state, "on")) {
  			led->cdev.brightness = LED_FULL;
  		} else if (!strcmp(state, "keep")) {
  			void __iomem *mode;
-			unsigned long val, shift;
+			unsigned long val, shift, flags;
 
  			shift = bcm6328_pin2shift(led->pin);
  			if (shift / 16)

@@ -300,9 +298,12 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  			else
  				mode = mem + BCM6328_REG_MODE_LO;
 
+			spin_lock_irqsave(lock, flags);
  			val = bcm6328_led_read(mode) >>
  			      BCM6328_LED_SHIFT(shift % 16);
  			val &= BCM6328_LED_MODE_MASK;
+			spin_unlock_irqrestore(lock, flags);
+
  			if ((led->active_low && val == BCM6328_LED_MODE_ON) ||
  			    (!led->active_low && val == BCM6328_LED_MODE_OFF))
  				led->cdev.brightness = LED_FULL;

drivers/leds/leds-bcm6328.c +1 -1

-	spin_unlock_irqrestore(lock, flags);
+	bcm6328_led_set(&led->cdev, led->cdev.brightness);
 
  	led->cdev.brightness_set = bcm6328_led_set;
  	led->cdev.blink_set = bcm6328_blink_set;

Hi Simon,

Thanks for the patch. Generally this patch touches two areas - replacement of redundant code with bcm6328_led_set, and locking reorganization. These should be split into two separate patches. Nonetheless, I've noticed some issues in the code, please refer below.

Quoted 59 lines · Simon Arlott

When ensuring a consistent initial LED state in bcm6328_led (as they may be blinking instead of on/off), the LED register is set using a copy of bcm6328_led_set(). To avoid further errors relating to active low handling, call this function directly instead.

As bcm6328_led_set() expects to acquire the spinlock, narrow the locking to only cover reading of the current state. There is no need to hold the spinlock between reading the current value and setting it again because the LED device has not yet been registered.

Signed-off-by Simon Arlott <[email protected]>

---
  drivers/leds/leds-bcm6328.c | 14 +++++---------
  1 file changed, 5 insertions(+), 9 deletions(-)

drivers/leds/leds-bcm6328.c +1 -3

index c7ea5c6..db327bd 100644
@@ -264,7 +264,6 @@ static int bcm6328_led(struct device *dev, struct 
 device_node *nc, u32 reg,
                 unsigned long *blink_leds, unsigned long *blink_delay)
  {
      struct bcm6328_led *led;
-    unsigned long flags;
      const char *state;
      int rc;

@@ -286,13 +285,12 @@ static int bcm6328_led(struct device *dev, 
 struct device_node *nc, u32 reg,
                              "linux,default-trigger",
                              NULL);
 
-    spin_lock_irqsave(lock, flags);
      if (!of_property_read_string(nc, "default-state", &state)) {
          if (!strcmp(state, "on")) {
              led->cdev.brightness = LED_FULL;
          } else if (!strcmp(state, "keep")) {
              void __iomem *mode;
-            unsigned long val, shift;
+            unsigned long val, shift, flags;
 
              shift = bcm6328_pin2shift(led->pin);

              if (shift / 16)

drivers/leds/leds-bcm6328.c +3 -0

@@ -300,9 +298,12 @@ static int bcm6328_led(struct device *dev, 
 struct device_node *nc, u32 reg,
              else
                  mode = mem + BCM6328_REG_MODE_LO;
 
+            spin_lock_irqsave(lock, flags);
              val = bcm6328_led_read(mode) >>
                    BCM6328_LED_SHIFT(shift % 16);
              val &= BCM6328_LED_MODE_MASK;
+            spin_unlock_irqrestore(lock, flags);
+
              if ((led->active_low && val == BCM6328_LED_MODE_ON) ||
                  (!led->active_low && val == BCM6328_LED_MODE_OFF))

                  led->cdev.brightness = LED_FULL;

drivers/leds/leds-bcm6328.c static int bcm6328_led(struct device *dev, · line 323

Quoted 9 lines

drivers/leds/leds-bcm6328.c +0 -5

@@ -315,12 +316,7 @@ static int bcm6328_led(struct device *dev, 
 struct device_node *nc, u32 reg,
          led->cdev.brightness = LED_OFF;
      }
 
-    if ((led->active_low && led->cdev.brightness == LED_FULL) ||
-        (!led->active_low && led->cdev.brightness == LED_OFF))
-        bcm6328_led_mode(led, BCM6328_LED_MODE_ON);
-    else
-        bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);

There are some problems with active_low mode here, I didn't recognize earlier.

I'd expect that active_low implies reverse logic, i.e.:

LED_FULL -> bcm6328_led_mode(led, BCM6328_LED_MODE_OFF); LED_OFF -> bcm6328_led_mode(led, BCM6328_LED_MODE_ON);

Let's take a look at bcm6328_led_set:

        if ((led->active_low && value == LED_OFF) ||
            (!led->active_low && value != LED_OFF))
                bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
        else
                bcm6328_led_mode(led, BCM6328_LED_MODE_ON);

which, for active_low case, boils down to:

LED_FULL -> bcm6328_led_mode(led, BCM6328_LED_MODE_ON); LED_OFF -> bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);

and for !active_low case to:

LED_FULL -> bcm6328_led_mode(led, BCM6328_LED_MODE_OFF); LED_OFF -> bcm6328_led_mode(led, BCM6328_LED_MODE_ON);

so, this is the other way round.

In bcm6328_led we have:

    if ((led->active_low && val == BCM6328_LED_MODE_ON) ||
        (!led->active_low && val == BCM6328_LED_MODE_OFF))
          led->cdev.brightness = LED_FULL;
    else
        led->cdev.brightness = LED_OFF;

which, for active_low case, boils down to:

BCM6328_LED_MODE_ON -> led->cdev.brightness = LED_FULL BCM6328_LED_MODE_OFF -> led->cdev.brightness = LED_OFF

and for !active_low case to:

BCM6328_LED_MODE_ON -> led->cdev.brightness = LED_OFF BCM6328_LED_MODE_OFF -> led->cdev.brightness = LED_FULL

again, the other way round.

All this looks like active_low really means active high. Correct me if I'm wrong.

Alvaro, Jonas, could you also help to clarify this discrepancy?

Quoted 6 lines

drivers/leds/leds-bcm6328.c +1 -1

-    spin_unlock_irqrestore(lock, flags);
+    bcm6328_led_set(&led->cdev, led->cdev.brightness);
 
      led->cdev.brightness_set = bcm6328_led_set;

      led->cdev.blink_set = bcm6328_blink_set;

Hello Jacek,

BCM6328_LED_MODE_ON and BCM6328_LED_MODE_OFF values were extracted from Broadcom's GPL code, in which they assume leds are active low by default. I can confirm the code is correct as it is right now, since those values match the active high / low values of the LEDs managed by GPIO instead of by using this driver.

Quoted 141 lines

Hi Simon,

Thanks for the patch. Generally this patch touches two areas - replacement of redundant code with bcm6328_led_set, and locking reorganization. These should be split into two separate patches. Nonetheless, I've noticed some issues in the code, please refer below.

Quoted 60 lines · Simon Arlott

When ensuring a consistent initial LED state in bcm6328_led (as they may be blinking instead of on/off), the LED register is set using a copy of bcm6328_led_set(). To avoid further errors relating to active low handling,
call this function directly instead.

As bcm6328_led_set() expects to acquire the spinlock, narrow the locking to only cover reading of the current state. There is no need to hold the spinlock between reading the current value and setting it again because the LED device has not yet been registered.

Signed-off-by Simon Arlott <[email protected]>

---
  drivers/leds/leds-bcm6328.c | 14 +++++---------
  1 file changed, 5 insertions(+), 9 deletions(-)

drivers/leds/leds-bcm6328.c +1 -3

index c7ea5c6..db327bd 100644
@@ -264,7 +264,6 @@ static int bcm6328_led(struct device *dev, struct
 device_node *nc, u32 reg,
                 unsigned long *blink_leds, unsigned long *blink_delay)
  {
      struct bcm6328_led *led;
-    unsigned long flags;
      const char *state;
      int rc;

@@ -286,13 +285,12 @@ static int bcm6328_led(struct device *dev,
 struct device_node *nc, u32 reg,
                              "linux,default-trigger",
                              NULL);
 
-    spin_lock_irqsave(lock, flags);
      if (!of_property_read_string(nc, "default-state", &state)) {
          if (!strcmp(state, "on")) {
              led->cdev.brightness = LED_FULL;
          } else if (!strcmp(state, "keep")) {
              void __iomem *mode;
-            unsigned long val, shift;
+            unsigned long val, shift, flags;
 
              shift = bcm6328_pin2shift(led->pin);

              if (shift / 16)

drivers/leds/leds-bcm6328.c +3 -0

@@ -300,9 +298,12 @@ static int bcm6328_led(struct device *dev,
 struct device_node *nc, u32 reg,
              else
                  mode = mem + BCM6328_REG_MODE_LO;
 
+            spin_lock_irqsave(lock, flags);
              val = bcm6328_led_read(mode) >>
                    BCM6328_LED_SHIFT(shift % 16);
              val &= BCM6328_LED_MODE_MASK;
+            spin_unlock_irqrestore(lock, flags);
+
              if ((led->active_low && val == BCM6328_LED_MODE_ON) ||
                  (!led->active_low && val == BCM6328_LED_MODE_OFF))

                  led->cdev.brightness = LED_FULL;

drivers/leds/leds-bcm6328.c static int bcm6328_led(struct device *dev, · line 323

Quoted 9 lines

drivers/leds/leds-bcm6328.c +0 -5

@@ -315,12 +316,7 @@ static int bcm6328_led(struct device *dev,
 struct device_node *nc, u32 reg,
          led->cdev.brightness = LED_OFF;
      }
 
-    if ((led->active_low && led->cdev.brightness == LED_FULL) ||
-        (!led->active_low && led->cdev.brightness == LED_OFF))
-        bcm6328_led_mode(led, BCM6328_LED_MODE_ON);
-    else
-        bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);

There are some problems with active_low mode here, I didn't recognize earlier.

I'd expect that active_low implies reverse logic, i.e.:

LED_FULL -> bcm6328_led_mode(led, BCM6328_LED_MODE_OFF); LED_OFF -> bcm6328_led_mode(led, BCM6328_LED_MODE_ON);

Let's take a look at bcm6328_led_set:

        if ((led->active_low && value == LED_OFF) ||
            (!led->active_low && value != LED_OFF))
                bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
        else
                bcm6328_led_mode(led, BCM6328_LED_MODE_ON);

which, for active_low case, boils down to:

LED_FULL -> bcm6328_led_mode(led, BCM6328_LED_MODE_ON); LED_OFF -> bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);

and for !active_low case to:

LED_FULL -> bcm6328_led_mode(led, BCM6328_LED_MODE_OFF); LED_OFF -> bcm6328_led_mode(led, BCM6328_LED_MODE_ON);

so, this is the other way round.

In bcm6328_led we have:

    if ((led->active_low && val == BCM6328_LED_MODE_ON) ||
        (!led->active_low && val == BCM6328_LED_MODE_OFF))
          led->cdev.brightness = LED_FULL;
    else
        led->cdev.brightness = LED_OFF;

which, for active_low case, boils down to:

BCM6328_LED_MODE_ON -> led->cdev.brightness = LED_FULL BCM6328_LED_MODE_OFF -> led->cdev.brightness = LED_OFF

and for !active_low case to:

BCM6328_LED_MODE_ON -> led->cdev.brightness = LED_OFF BCM6328_LED_MODE_OFF -> led->cdev.brightness = LED_FULL

again, the other way round.

All this looks like active_low really means active high. Correct me if I'm wrong.

Alvaro, Jonas, could you also help to clarify this discrepancy?

Quoted 6 lines

drivers/leds/leds-bcm6328.c +1 -1

-    spin_unlock_irqrestore(lock, flags);
+    bcm6328_led_set(&led->cdev, led->cdev.brightness);
 
      led->cdev.brightness_set = bcm6328_led_set;

      led->cdev.blink_set = bcm6328_blink_set;

Quoted 5 lines · Álvaro Fernández Rojas

BCM6328_LED_MODE_ON and BCM6328_LED_MODE_OFF values were extracted from Broadcom's GPL code, in which they assume leds are active low by default. I can confirm the code is correct as it is right now, since those values match the active high / low values of the LEDs managed by GPIO instead of by using this driver.

BCM6328_LED_MODE_ON and BCM6328_LED_MODE_OFF should represent the values that actually set the LED state according to the current logic. Otherwise it will confuse people who will be analyzing this code. We are interested in the logic as it is seen from this driver's perspective and not GPIO perspective.

IMO the values should be swapped.

The values of BCM6328_LED_MODE_ON and BCM6328_LED_MODE_OFF were named for active low LEDs. These should be swapped so that they are named for the default case of active high LEDs.

Signed-off-by Simon Arlott <[email protected]>

---

Quoted 7 lines · Jacek Anaszewski

Quoted 5 lines · Álvaro Fernández Rojas

BCM6328_LED_MODE_ON and BCM6328_LED_MODE_OFF values were extracted from Broadcom's GPL code, in which they assume leds are active low by default. I can confirm the code is correct as it is right now, since those values match the active high / low values of the LEDs managed by GPIO instead of by using this driver.

Quoted 7 lines

BCM6328_LED_MODE_ON and BCM6328_LED_MODE_OFF should represent the values that actually set the LED state according to the current logic. Otherwise it will confuse people who will be analyzing this code. We are interested in the logic as it is seen from this driver's perspective and not GPIO perspective.

IMO the values should be swapped.

  drivers/leds/leds-bcm6328.c | 12 ++++++------
  1 file changed, 6 insertions(+), 6 deletions(-)

drivers/leds/leds-bcm6328.c +4 -4

index 95d0cf9..0329dee 100644
@@ -48,10 +48,10 @@
  					 BCM6328_SERIAL_LED_SHIFT_DIR)
 
  #define BCM6328_LED_MODE_MASK		3
-#define BCM6328_LED_MODE_OFF		0
+#define BCM6328_LED_MODE_ON		0
  #define BCM6328_LED_MODE_FAST		1
  #define BCM6328_LED_MODE_BLINK		2
-#define BCM6328_LED_MODE_ON		3
+#define BCM6328_LED_MODE_OFF		3
  #define BCM6328_LED_SHIFT(X)		((X) << 1)
 
  /**

@@ -126,9 +126,9 @@ static void bcm6328_led_set(struct led_classdev *led_cdev,
  	*(led->blink_leds) &= ~BIT(led->pin);
  	if ((led->active_low && value == LED_OFF) ||
  	    (!led->active_low && value != LED_OFF))
-		bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
-	else
  		bcm6328_led_mode(led, BCM6328_LED_MODE_ON);
+	else
+		bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
  	spin_unlock_irqrestore(led->lock, flags);
  }
 

When ensuring a consistent initial LED state in bcm6328_led (as they may be blinking instead of on/off), the LED register is set using an inverted copy of bcm6328_led_set(). To avoid further errors relating to active low handling, call this function directly instead.

Signed-off-by Simon Arlott <[email protected]>

---
I've decided not to move the locking as it should really cover the setting of led->cdev.brightness too (not that it matters as the device is not yet registered).

  drivers/leds/leds-bcm6328.c | 8 ++------
  1 file changed, 2 insertions(+), 6 deletions(-)

drivers/leds/leds-bcm6328.c +0 -0

index c7ea5c6..95d0cf9 100644
@@ -314,14 +314,10 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  	} else {
  		led->cdev.brightness = LED_OFF;
  	}

drivers/leds/leds-bcm6328.c +0 -0

  	led->cdev.brightness_set = bcm6328_led_set;
  	led->cdev.blink_set = bcm6328_blink_set;
 

When ensuring a consistent initial LED state in bcm6328_led (as they may be blinking instead of on/off), the LED register is set using an inverted copy of bcm6328_led_set(). To avoid further errors relating to active low handling, call this function directly instead.

As bcm6328_led_set() acquires the same spinlock again when updating the register, it is called after unlocking.

Signed-off-by Simon Arlott <[email protected]>

---
  drivers/leds/leds-bcm6328.c | 8 ++------
  1 file changed, 2 insertions(+), 6 deletions(-)

drivers/leds/leds-bcm6328.c +2 -6

index c7ea5c6..95d0cf9 100644
@@ -314,14 +314,10 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  	} else {
  		led->cdev.brightness = LED_OFF;
  	}
-
-	if ((led->active_low && led->cdev.brightness == LED_FULL) ||
-	    (!led->active_low && led->cdev.brightness == LED_OFF))
-		bcm6328_led_mode(led, BCM6328_LED_MODE_ON);
-	else
-		bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
  	spin_unlock_irqrestore(lock, flags);
 
+	bcm6328_led_set(&led->cdev, led->cdev.brightness);
+
  	led->cdev.brightness_set = bcm6328_led_set;
  	led->cdev.blink_set = bcm6328_blink_set;
 

Still wrong, you are setting the led value after unlocking the spinlock.

Quoted 34 lines

When ensuring a consistent initial LED state in bcm6328_led (as they may be blinking instead of on/off), the LED register is set using an inverted copy of bcm6328_led_set(). To avoid further errors relating to active low handling, call this function directly instead.

As bcm6328_led_set() acquires the same spinlock again when updating the register, it is called after unlocking.

Signed-off-by Simon Arlott <[email protected]>

---
  drivers/leds/leds-bcm6328.c | 8 ++------
  1 file changed, 2 insertions(+), 6 deletions(-)

drivers/leds/leds-bcm6328.c +2 -6

index c7ea5c6..95d0cf9 100644
@@ -314,14 +314,10 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  	} else {
  		led->cdev.brightness = LED_OFF;
  	}
-
-	if ((led->active_low && led->cdev.brightness == LED_FULL) ||
-	    (!led->active_low && led->cdev.brightness == LED_OFF))
-		bcm6328_led_mode(led, BCM6328_LED_MODE_ON);
-	else
-		bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
  	spin_unlock_irqrestore(lock, flags);
 
+	bcm6328_led_set(&led->cdev, led->cdev.brightness);
+
  	led->cdev.brightness_set = bcm6328_led_set;
  	led->cdev.blink_set = bcm6328_blink_set;
 

Quoted 1 line · Álvaro Fernández Rojas

Still wrong, you are setting the led value after unlocking the spinlock.

I have to unlock it because bcm6328_led_set() locks that spinlock.

Quoted 36 lines · Simon Arlott

Quoted 34 lines

When ensuring a consistent initial LED state in bcm6328_led (as they may be blinking instead of on/off), the LED register is set using an inverted copy of bcm6328_led_set(). To avoid further errors relating to active low handling, call this function directly instead.

As bcm6328_led_set() acquires the same spinlock again when updating the register, it is called after unlocking.

Signed-off-by Simon Arlott <[email protected]>

---
   drivers/leds/leds-bcm6328.c | 8 ++------
   1 file changed, 2 insertions(+), 6 deletions(-)

drivers/leds/leds-bcm6328.c +2 -6

index c7ea5c6..95d0cf9 100644
@@ -314,14 +314,10 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
   	} else {
   		led->cdev.brightness = LED_OFF;
   	}
-
-	if ((led->active_low && led->cdev.brightness == LED_FULL) ||
-	    (!led->active_low && led->cdev.brightness == LED_OFF))
-		bcm6328_led_mode(led, BCM6328_LED_MODE_ON);
-	else
-		bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
   	spin_unlock_irqrestore(lock, flags);
 
+	bcm6328_led_set(&led->cdev, led->cdev.brightness);
+
   	led->cdev.brightness_set = bcm6328_led_set;
   	led->cdev.blink_set = bcm6328_blink_set;
 

Hi Alvaro, Simon,

Quoted 4 lines · Simon Arlott

Quoted 1 line · Álvaro Fernández Rojas

Still wrong, you are setting the led value after unlocking the spinlock.

I have to unlock it because bcm6328_led_set() locks that spinlock.

Commit message from the first version of the patch justified that properly. It should be preserved in the final patch:

As bcm6328_led_set() expects to acquire the spinlock, narrow the locking to only cover reading of the current state. There is no need to hold the spinlock between reading the current value and setting it again because the LED device has not yet been registered.

Quoted 42 lines

Quoted 40 lines · Simon Arlott

Quoted 38 lines

When ensuring a consistent initial LED state in bcm6328_led (as they may
be blinking instead of on/off), the LED register is set using an inverted
copy of bcm6328_led_set(). To avoid further errors relating to active low
handling, call this function directly instead.

As bcm6328_led_set() acquires the same spinlock again when updating the register, it is called after unlocking.

Signed-off-by Simon Arlott <[email protected]>

---
   drivers/leds/leds-bcm6328.c | 8 ++------
   1 file changed, 2 insertions(+), 6 deletions(-)

drivers/leds/leds-bcm6328.c +2 -6

index c7ea5c6..95d0cf9 100644
@@ -314,14 +314,10 @@ static int bcm6328_led(struct device *dev,
 struct device_node *nc, u32 reg,
       } else {
           led->cdev.brightness = LED_OFF;
       }
-
-    if ((led->active_low && led->cdev.brightness == LED_FULL) ||
-        (!led->active_low && led->cdev.brightness == LED_OFF))
-        bcm6328_led_mode(led, BCM6328_LED_MODE_ON);
-    else
-        bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
       spin_unlock_irqrestore(lock, flags);
 
+    bcm6328_led_set(&led->cdev, led->cdev.brightness);
+
       led->cdev.brightness_set = bcm6328_led_set;
       led->cdev.blink_set = bcm6328_blink_set;

Quoted 9 lines · Jacek Anaszewski

Quoted 4 lines · Simon Arlott

Quoted 1 line · Álvaro Fernández Rojas

Still wrong, you are setting the led value after unlocking the spinlock.

I have to unlock it because bcm6328_led_set() locks that spinlock.

Commit message from the first version of the patch justified that properly. It should be preserved in the final patch:

Quoted 4 lines

As bcm6328_led_set() expects to acquire the spinlock, narrow the locking to only cover reading of the current state. There is no need to hold the spinlock between reading the current value and setting it again because the LED device has not yet been registered.

Hmm, if so, then spin_lock in bcm6328_led isn't needed at all, as it is guaranteed that no concurrent process will be executing this function.

When ensuring a consistent initial LED state in bcm6328_led (as they may be blinking instead of on/off), the LED register is set using an inverted copy of bcm6328_led_set(). To avoid further errors relating to active low handling, call this function directly instead.

As bcm6328_led_set() expects to acquire the spinlock, call it after unlocking. There is no need to hold the spinlock between reading the current value and setting it again because the LED device has not yet been registered.

Signed-off-by Simon Arlott <[email protected]>

---

Quoted 15 lines · Jacek Anaszewski

Quoted 13 lines · Jacek Anaszewski

Quoted 4 lines · Simon Arlott

Quoted 1 line · Álvaro Fernández Rojas

Still wrong, you are setting the led value after unlocking the spinlock.

I have to unlock it because bcm6328_led_set() locks that spinlock.

Commit message from the first version of the patch justified that properly. It should be preserved in the final patch:

As bcm6328_led_set() expects to acquire the spinlock, narrow the locking to only cover reading of the current state. There is no need to hold the spinlock between reading the current value and setting it again because the LED device has not yet been registered.

Quoted 3 lines

Hmm, if so, then spin_lock in bcm6328_led isn't needed at all, as it is guaranteed that no concurrent process will be executing this function.

No, it's still required because it has to protect the read/modify/write for all the other LED devices that use the same register.

  drivers/leds/leds-bcm6328.c | 8 ++------
  1 file changed, 2 insertions(+), 6 deletions(-)

drivers/leds/leds-bcm6328.c +2 -6

index c7ea5c6..95d0cf9 100644
@@ -314,14 +314,10 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  	} else {
  		led->cdev.brightness = LED_OFF;
  	}
-
-	if ((led->active_low && led->cdev.brightness == LED_FULL) ||
-	    (!led->active_low && led->cdev.brightness == LED_OFF))
-		bcm6328_led_mode(led, BCM6328_LED_MODE_ON);
-	else
-		bcm6328_led_mode(led, BCM6328_LED_MODE_OFF);
  	spin_unlock_irqrestore(lock, flags);
 
+	bcm6328_led_set(&led->cdev, led->cdev.brightness);
+
  	led->cdev.brightness_set = bcm6328_led_set;
  	led->cdev.blink_set = bcm6328_blink_set;
 

When ensuring a consistent initial LED state in bcm6328_led (as they may be blinking instead of on/off), the LED register is set using an inverted copy of bcm6328_led_set(). To avoid further errors relating to active low handling, call this function directly instead.

As bcm6328_led_set() acquires the same spinlock again when updating the register, it is called after unlocking.

Signed-off-by Simon Arlott <[email protected]>

---
  drivers/leds/leds-bcm6328.c | 8 ++------
  1 file changed, 2 insertions(+), 6 deletions(-)

drivers/leds/leds-bcm6328.c +0 -3

index c7ea5c6..95d0cf9 100644
@@ -314,14 +314,10 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg,
  	} else {
  		led->cdev.brightness = LED_OFF;
  	}
-
-	if ((led->active_low && led->cdev.brightness == LED_FULL) ||
-	    (!led->active_low && led->cdev.brightness == LED_OFF))