linux-kernel - Re: [PATCH] leds: Ensure hardware blinking turns off when requested

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Message-ID: <CAPxw_W_10Z173z+s4DYDc6A1raVff2B8EhOWxg9AVgoqj-eS+A@mail.gmail.com>
Date:   Wed, 5 Apr 2023 17:44:37 +0100
From:   Lee Jones <lee@...nel.org>
To:     Eddie James <eajames@...ux.ibm.com>
Cc:     pavel@....cz, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] leds: Ensure hardware blinking turns off when requested

Apologies for any chaos this may cause, I'm replying from Gmail since
this doesn't appear to be in my inbox.

On Wed, 5 Apr 2023 at 17:26, Eddie James <eajames@...ux.ibm.com> wrote:
>
>
> On 5/20/22 12:11, Eddie James wrote:
> > If an LED is blinking through the hardware and the trigger is deactivated,
> > the driver will set the brightness to 0 to disable blinking. However, if
> > the LED driver doesn't support non-blocking operations, the request for
> > setting brightness to 0 will get queued. Then if a user requests a new
> > non-zero brightness before the request for 0 brightness is executed, the
> > LED blinking will not get disabled since the brightness will simply be
> > updated.
> > Fix this by flushing the workqueue before updating the requested
> > brightness.
>
>
> I just realized this never made it anywhere. Pavel, any thoughts?

Submit a [RESEND] please.

Also, please ensure you re-run get_maintainer.pl before doing so.

> > Fixes: 4d71a4a12b13 ("leds: Add support for setting brightness in a synchronous way")
> > Signed-off-by: Eddie James <eajames@...ux.ibm.com>
> > ---
> >   drivers/leds/led-class.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> > index 6a8ea94834fa..861a1cb5df5b 100644
> > --- a/drivers/leds/led-class.c
> > +++ b/drivers/leds/led-class.c
> > @@ -55,6 +55,8 @@ static ssize_t brightness_store(struct device *dev,
> >
> >       if (state == LED_OFF)
> >               led_trigger_remove(led_cdev);
> > +     /* flush out any request to disable blinking */
> > +     flush_work(&led_cdev->set_brightness_work);
> >       led_set_brightness(led_cdev, state);
> >       flush_work(&led_cdev->set_brightness_work);
> >