[PATCH 2/4] leds-lp5523: set the brightness to 0 forcely on removing the driver

[PATCH 2/4] leds-lp5523: set the brightness to 0 forcely on removing the driver

[Kim, Milo]

Turning off the brightness of each channel is required
when removing the driver.

So use flush_work_sync() rather than cancel_work_sync() to wait for
unhandled brightness works.

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
---
 drivers/leds/leds-lp5523.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/leds-lp5523.c b/drivers/leds/leds-lp5523.c
index 9fd9a92..f090819 100644
--- a/drivers/leds/leds-lp5523.c
+++ b/drivers/leds/leds-lp5523.c
@@ -974,7 +974,7 @@ static int __devinit lp5523_probe(struct i2c_client *client,
 fail2:
 	for (i = 0; i < chip->num_leds; i++) {
 		led_classdev_unregister(&chip->leds[i].cdev);
-		cancel_work_sync(&chip->leds[i].brightness_work);
+		flush_work_sync(&chip->leds[i].brightness_work);
 	}
 fail1:
 	if (pdata->enable)
@@ -993,7 +993,7 @@ static int lp5523_remove(struct i2c_client *client)
 
 	for (i = 0; i < chip->num_leds; i++) {
 		led_classdev_unregister(&chip->leds[i].cdev);
-		cancel_work_sync(&chip->leds[i].brightness_work);
+		flush_work_sync(&chip->leds[i].brightness_work);
 	}
 
 	if (chip->pdata->enable)
-- 
1.7.2.5


Best Regards,
Milo

Re: [PATCH 2/4] leds-lp5523: set the brightness to 0 forcely on removing the driver

[Bryan Wu]

On Tue, Aug 21, 2012 at 5:03 PM, Kim, Milo <Milo.Kim@ti.com> wrote:
> Turning off the brightness of each channel is required
> when removing the driver.
>
> So use flush_work_sync() rather than cancel_work_sync() to wait for
> unhandled brightness works.

Hmmm, I think we still should use cancel_work() here based on your
idea. Please find the patch from Tejun and add him to this loop
[PATCH 4/6] workqueue: deprecate flush[_delayed]_work_sync()
---
Before this patchset,

 flush_work()

        flush the last queued instance of the work item.  If it got
        queued on multple CPUs, it only considers the last queued
        instance.  The work item could still be executing on other
        CPUs and the flush might become noop if there are competing
        queueing operation on another CPU.

 flush_work_sync()

        flush_work() + wait for executing instances on all CPUs.  The
        flush_work() part may still become noop if there's competing
        queueing operation.

 cancel_work()

        Dequeue the work item if it's pending.  Doesn't care about
        whether it's executing or not.

 cancel_work_sync()

        cancel_work() + flush_work_sync().


After this patchset,

 flush_work()

        flush the work item.  Any queueing happened previously is
        guaranteed to have finished execution on return.  If no
        further queueing happened after flush started, the work item
        is guaranteed to be idle on return.

 cancel_work()

        Same as before.

 cancel_work_sync()

        cancel_work() followed by flush_work().  The same semantics as
        del_timer_sync().
---

cancel_work_sync() won't execute the work item at all just cancel
them, but flush will execute them and return.

-Bryan

>
> Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
> ---
>  drivers/leds/leds-lp5523.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/leds/leds-lp5523.c b/drivers/leds/leds-lp5523.c
> index 9fd9a92..f090819 100644
> --- a/drivers/leds/leds-lp5523.c
> +++ b/drivers/leds/leds-lp5523.c
> @@ -974,7 +974,7 @@ static int __devinit lp5523_probe(struct i2c_client *client,
>  fail2:
>         for (i = 0; i < chip->num_leds; i++) {
>                 led_classdev_unregister(&chip->leds[i].cdev);
> -               cancel_work_sync(&chip->leds[i].brightness_work);
> +               flush_work_sync(&chip->leds[i].brightness_work);
>         }
>  fail1:
>         if (pdata->enable)
> @@ -993,7 +993,7 @@ static int lp5523_remove(struct i2c_client *client)
>
>         for (i = 0; i < chip->num_leds; i++) {
>                 led_classdev_unregister(&chip->leds[i].cdev);
> -               cancel_work_sync(&chip->leds[i].brightness_work);
> +               flush_work_sync(&chip->leds[i].brightness_work);
>         }
>
>         if (chip->pdata->enable)
> --
> 1.7.2.5
>
>
> Best Regards,
> Milo
>
>



-- 
Bryan Wu <bryan.wu@canonical.com>
Kernel Developer    +86.186-168-78255 Mobile
Canonical Ltd.      www.canonical.com
Ubuntu - Linux for human beings | www.ubuntu.com

RE: [PATCH 2/4] leds-lp5523: set the brightness to 0 forcely on removing the driver

[Kim, Milo]

> Hmmm, I think we still should use cancel_work() here based on your
> idea. Please find the patch from Tejun and add him to this loop
> [PATCH 4/6] workqueue: deprecate flush[_delayed]_work_sync()
> ---
> Before this patchset,
> 
>  flush_work()
> 
>         flush the last queued instance of the work item.  If it got
>         queued on multple CPUs, it only considers the last queued
>         instance.  The work item could still be executing on other
>         CPUs and the flush might become noop if there are competing
>         queueing operation on another CPU.
> 
>  flush_work_sync()
> 
>         flush_work() + wait for executing instances on all CPUs.  The
>         flush_work() part may still become noop if there's competing
>         queueing operation.
> 
>  cancel_work()
> 
>         Dequeue the work item if it's pending.  Doesn't care about
>         whether it's executing or not.
> 
>  cancel_work_sync()
> 
>         cancel_work() + flush_work_sync().
> 
> 
> After this patchset,
> 
>  flush_work()
> 
>         flush the work item.  Any queueing happened previously is
>         guaranteed to have finished execution on return.  If no
>         further queueing happened after flush started, the work item
>         is guaranteed to be idle on return.
> 
>  cancel_work()
> 
>         Same as before.
> 
>  cancel_work_sync()
> 
>         cancel_work() followed by flush_work().  The same semantics as
>         del_timer_sync().
> ---
> 
> cancel_work_sync() won't execute the work item at all just cancel
> them, but flush will execute them and return.
> 

Thanks a lot for the updates!

Then, I think flush_work() should be used for executing remaining brightness work
rather than cancel_work_sync().

Best Regards,
Milo

Re: [PATCH 2/4] leds-lp5523: set the brightness to 0 forcely on removing the driver

[Bryan Wu]

On Wed, Aug 22, 2012 at 1:46 PM, Kim, Milo <Milo.Kim@ti.com> wrote:
>> Hmmm, I think we still should use cancel_work() here based on your
>> idea. Please find the patch from Tejun and add him to this loop
>> [PATCH 4/6] workqueue: deprecate flush[_delayed]_work_sync()
>> ---
>> Before this patchset,
>>
>>  flush_work()
>>
>>         flush the last queued instance of the work item.  If it got
>>         queued on multple CPUs, it only considers the last queued
>>         instance.  The work item could still be executing on other
>>         CPUs and the flush might become noop if there are competing
>>         queueing operation on another CPU.
>>
>>  flush_work_sync()
>>
>>         flush_work() + wait for executing instances on all CPUs.  The
>>         flush_work() part may still become noop if there's competing
>>         queueing operation.
>>
>>  cancel_work()
>>
>>         Dequeue the work item if it's pending.  Doesn't care about
>>         whether it's executing or not.
>>
>>  cancel_work_sync()
>>
>>         cancel_work() + flush_work_sync().
>>
>>
>> After this patchset,
>>
>>  flush_work()
>>
>>         flush the work item.  Any queueing happened previously is
>>         guaranteed to have finished execution on return.  If no
>>         further queueing happened after flush started, the work item
>>         is guaranteed to be idle on return.
>>
>>  cancel_work()
>>
>>         Same as before.
>>
>>  cancel_work_sync()
>>
>>         cancel_work() followed by flush_work().  The same semantics as
>>         del_timer_sync().
>> ---
>>
>> cancel_work_sync() won't execute the work item at all just cancel
>> them, but flush will execute them and return.
>>
>
> Thanks a lot for the updates!
>
> Then, I think flush_work() should be used for executing remaining brightness work
> rather than cancel_work_sync().
>

Yeah, I agree here. I made a mistake about your original patch's description.

-Bryan