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| Started by | Álvaro Fernández Rojas <noltari@gmail.com> |
|---|---|
| First post | 2015-11-04 16:50 +0100 |
| Last post | 2015-11-15 14:40 +0100 |
| Articles | 4 — 3 participants |
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Re: [PATCH] leds-bcm6328: Reuse bcm6328_led_set() instead of copying its functionality Álvaro Fernández Rojas <noltari@gmail.com> - 2015-11-04 16:50 +0100
Re: [PATCH] leds-bcm6328: Reuse bcm6328_led_set() instead of copying its functionality Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-11-05 11:50 +0100
[PATCH 2/2] leds-bcm6328: Swap LED ON and OFF definitions Simon Arlott <simon@fire.lp0.eu> - 2015-11-15 14:40 +0100
[PATCH 1/2] leds-bcm6328: Reuse bcm6328_led_set() instead of copying its functionality Simon Arlott <simon@fire.lp0.eu> - 2015-11-15 14:40 +0100
| From | Álvaro Fernández Rojas <noltari@gmail.com> |
|---|---|
| Date | 2015-11-04 16:50 +0100 |
| Subject | Re: [PATCH] leds-bcm6328: Reuse bcm6328_led_set() instead of copying its functionality |
| Message-ID | <qr8tX-2jQ-5@gated-at.bofh.it> |
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.
Regards,
Álvaro.
El 04/11/2015 a las 16:41, Jacek Anaszewski escribió:
> 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.
>
> On 10/29/2015 08:48 PM, Simon Arlott wrote:
>> 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 <simon@fire.lp0.eu>
>> ---
>> drivers/leds/leds-bcm6328.c | 14 +++++---------
>> 1 file changed, 5 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/leds/leds-bcm6328.c b/drivers/leds/leds-bcm6328.c
>> index c7ea5c6..db327bd 100644
>> --- a/drivers/leds/leds-bcm6328.c
>> +++ b/drivers/leds/leds-bcm6328.c
>> @@ -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;
>> @@ -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?
>
>
>> - 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;
>>
>
>
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| From | Jacek Anaszewski <j.anaszewski@samsung.com> |
|---|---|
| Date | 2015-11-05 11:50 +0100 |
| Message-ID | <qrqhb-5qX-9@gated-at.bofh.it> |
| In reply to | #1262389 |
Hi Alvaro,
On 11/04/2015 04:46 PM, Álvaro Fernández Rojas wrote:
> 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.
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.
Best Regards,
Jacek Anaszewski
> El 04/11/2015 a las 16:41, Jacek Anaszewski escribió:
>> 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.
>>
>> On 10/29/2015 08:48 PM, Simon Arlott wrote:
>>> 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 <simon@fire.lp0.eu>
>>> ---
>>> drivers/leds/leds-bcm6328.c | 14 +++++---------
>>> 1 file changed, 5 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/drivers/leds/leds-bcm6328.c b/drivers/leds/leds-bcm6328.c
>>> index c7ea5c6..db327bd 100644
>>> --- a/drivers/leds/leds-bcm6328.c
>>> +++ b/drivers/leds/leds-bcm6328.c
>>> @@ -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;
>>> @@ -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?
>>
>>
>>> - 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;
>>>
>>
>>
>
>
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| From | Simon Arlott <simon@fire.lp0.eu> |
|---|---|
| Date | 2015-11-15 14:40 +0100 |
| Subject | [PATCH 2/2] leds-bcm6328: Swap LED ON and OFF definitions |
| Message-ID | <qv5Hc-20o-13@gated-at.bofh.it> |
| In reply to | #1263086 |
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 <simon@fire.lp0.eu> --- On 05/11/15 10:41, Jacek Anaszewski wrote: > On 11/04/2015 04:46 PM, Álvaro Fernández Rojas wrote: >> 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. drivers/leds/leds-bcm6328.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/leds/leds-bcm6328.c b/drivers/leds/leds-bcm6328.c index 95d0cf9..0329dee 100644 --- a/drivers/leds/leds-bcm6328.c +++ b/drivers/leds/leds-bcm6328.c @@ -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); } @@ -303,8 +303,8 @@ static int bcm6328_led(struct device *dev, struct device_node *nc, u32 reg, val = bcm6328_led_read(mode) >> BCM6328_LED_SHIFT(shift % 16); val &= BCM6328_LED_MODE_MASK; - if ((led->active_low && val == BCM6328_LED_MODE_ON) || - (!led->active_low && val == BCM6328_LED_MODE_OFF)) + if ((led->active_low && val == BCM6328_LED_MODE_OFF) || + (!led->active_low && val == BCM6328_LED_MODE_ON)) led->cdev.brightness = LED_FULL; else led->cdev.brightness = LED_OFF; -- 2.1.4 -- Simon Arlott -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Simon Arlott <simon@fire.lp0.eu> |
|---|---|
| Date | 2015-11-15 14:40 +0100 |
| Subject | [PATCH 1/2] leds-bcm6328: Reuse bcm6328_led_set() instead of copying its functionality |
| Message-ID | <qv5Hc-20o-15@gated-at.bofh.it> |
| In reply to | #1263086 |
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 <simon@fire.lp0.eu>
---
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(-)
diff --git a/drivers/leds/leds-bcm6328.c b/drivers/leds/leds-bcm6328.c
index c7ea5c6..95d0cf9 100644
--- a/drivers/leds/leds-bcm6328.c
+++ b/drivers/leds/leds-bcm6328.c
@@ -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;
--
2.1.4
--
Simon Arlott
--
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