Messages in this thread | | | Date | Mon, 23 Nov 2015 11:19:55 +0100 | From | Jacek Anaszewski <> | Subject | Re: [PATCH 1/2 (v3)] leds-bcm6328: Reuse bcm6328_led_set() instead of copying its functionality |
| |
On 11/22/2015 09:40 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 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 <simon@fire.lp0.eu> > --- > On 17/11/15 08:15, Jacek Anaszewski wrote: >> On 11/17/2015 09:06 AM, Jacek Anaszewski wrote: >>> On 11/17/2015 08:42 AM, Simon Arlott wrote: >>>> On 16/11/15 21:33, Álvaro Fernández Rojas wrote: >>>>> 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. >> >> 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.
Right, other already registered LED class devices can interfere.
> 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; > >
-- Best Regards, Jacek Anaszewski
| |