linux-kernel - Re: [PATCH AUTOSEL for 4.14 065/110] led: core: Fix brightness setting when setting delay

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Date:   Sun, 4 Feb 2018 15:49:06 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     Pavel Machek <pavel@....cz>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Matthieu CASTET <matthieu.castet@...rot.com>,
        "linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>
Subject: Re: [PATCH AUTOSEL for 4.14 065/110] led: core: Fix brightness
 setting when setting delay_off=0

On Sun, Feb 04, 2018 at 10:05:31AM +0100, Pavel Machek wrote:
>On Sun 2018-02-04 00:30:36, Sasha Levin wrote:
>> On Sat, Feb 03, 2018 at 09:35:26PM +0100, Pavel Machek wrote:
>> >On Sat 2018-02-03 18:00:59, Sasha Levin wrote:
>> >> From: Matthieu CASTET <matthieu.castet@...rot.com>
>> >>
>> >> [ Upstream commit 2b83ff96f51d0b039c4561b9f95c824d7bddb85c ]
>> >>
>> >> With the current code, the following sequence won't work :
>> >> echo timer > trigger
>> >>
>> >> echo 0 >  delay_off
>> >> * at this point we call
>> >> ** led_delay_off_store
>> >> ** led_blink_set
>> >> *** stop timer
>> >> ** led_blink_setup
>> >> ** led_set_software_blink
>> >> *** if !delay_on, led off
>> >> *** if !delay_off, set led_set_brightness_nosleep <--- LED_BLINK_SW is set but timer is stop
>> >> *** otherwise start timer/set LED_BLINK_SW flag
>> >>
>> >> echo xxx > brightness
>> >> * led_set_brightness
>> >> ** if LED_BLINK_SW
>> >> *** if brightness=0, led off
>> >> *** else apply brightness if next timer <--- timer is stop, and will never apply new setting
>> >> ** otherwise set led_set_brightness_nosleep
>> >>
>> >> To fix that, when we delete the timer, we should clear LED_BLINK_SW.
>> >
>> >Can you run the tests on the affected stable kernels? I have feeling
>> >that the problem described might not be present there.
>>
>> Hm, I don't seem to have HW to test that out. Maybe someone else does?
>
>Why are you submitting patches you have no way to test?

Because.... that's how the process works? -stable maintainers don't test
every single patch that goes in. Never happened and I doubt it ever
will.

>Plus... you don't have PC keyboard? You don't have thinkpad notebook?

Nope, all the (limited) testing I do happens in VMs, which don't expose
leds as far as I know.

-- 

Thanks,
Sasha