Re: [PATCH 1/2 (v2)] leds-bcm6328: Reuse bcm6328_led_set() instead of copying its functionality

[Jacek Anaszewski]

On 11/17/2015 09:06 AM, Jacek Anaszewski wrote:
> Hi Alvaro, Simon,
>
> On 11/17/2015 08:42 AM, Simon Arlott wrote:
> > On 16/11/15 21:33, Ãlvaro FernÃndez 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.

> > > El 16/11/2015 a las 21:24, Simon Arlott escribiÃ:
> > > > 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 <simon@xxxxxxxxxxx>
> > > > ---
> > > >    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
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