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Subject: Re: [PATCH AUTOSEL for 4.14 065/110] led: core: Fix brightness
 setting when setting delay_off=0
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Jacek Anaszewski <jacek.anaszewski@gmail.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>,
        Pavel Machek <pavel@ucw.cz>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        Matthieu CASTET <matthieu.castet@parrot.com>,
        "linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>
References: <20180203180015.29073-1-alexander.levin@microsoft.com>
 <20180203180015.29073-65-alexander.levin@microsoft.com>
 <20180203203525.GA5860@amd> <20180204003029.2lkcmh6wvzpnlrls@sasha-lappy>
 <20180204090531.GA29468@amd> <20180204111500.GB14797@kroah.com>
 <20180204171736.GA1388@amd> <20180206020210.m6gl7vai4p6azb6s@sasha-lappy>
 <713113d8-7662-d80c-c62f-af020469d0bf@gmail.com>
 <f072a5c1-95f1-e81b-c629-ebdea723e6f4@universe-factory.net>
 <20180312152811.GB16944@kroah.com>
From:   Matthias Schiffer <mschiffer@universe-factory.net>
Message-ID: <5747831a-b237-aa2c-cb47-9773cd2b5956@universe-factory.net>
Date:   Mon, 12 Mar 2018 16:45:43 +0100
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From: Matthias Schiffer <mschiffer@universe-factory.net>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>,
 Sasha Levin <Alexander.Levin@microsoft.com>, Pavel Machek <pavel@ucw.cz>,
 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
 "stable@vger.kernel.org" <stable@vger.kernel.org>,
 Matthieu CASTET <matthieu.castet@parrot.com>,
 "linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>
Message-ID: <5747831a-b237-aa2c-cb47-9773cd2b5956@universe-factory.net>
Subject: Re: [PATCH AUTOSEL for 4.14 065/110] led: core: Fix brightness
 setting when setting delay_off=0
References: <20180203180015.29073-1-alexander.levin@microsoft.com>
 <20180203180015.29073-65-alexander.levin@microsoft.com>
 <20180203203525.GA5860@amd> <20180204003029.2lkcmh6wvzpnlrls@sasha-lappy>
 <20180204090531.GA29468@amd> <20180204111500.GB14797@kroah.com>
 <20180204171736.GA1388@amd> <20180206020210.m6gl7vai4p6azb6s@sasha-lappy>
 <713113d8-7662-d80c-c62f-af020469d0bf@gmail.com>
 <f072a5c1-95f1-e81b-c629-ebdea723e6f4@universe-factory.net>
 <20180312152811.GB16944@kroah.com>
In-Reply-To: <20180312152811.GB16944@kroah.com>

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On 03/12/2018 04:28 PM, Greg KH wrote:
> On Mon, Mar 12, 2018 at 04:00:01PM +0100, Matthias Schiffer wrote:
>> On 02/06/2018 09:44 PM, Jacek Anaszewski wrote:
>>> On 02/06/2018 03:02 AM, Sasha Levin wrote:
>>>> On Sun, Feb 04, 2018 at 06:17:36PM +0100, Pavel Machek wrote:
>>>>>
>>>>>>>>>> *** if brightness=3D0, led off
>>>>>>>>>> *** else apply brightness if next timer <--- timer is stop, an=
d will never apply new setting
>>>>>>>>>> ** otherwise set led_set_brightness_nosleep
>>>>>>>>>>
>>>>>>>>>> To fix that, when we delete the timer, we should clear LED_BLI=
NK_SW.
>>>>>>>>>
>>>>>>>>> Can you run the tests on the affected stable kernels? I have fe=
eling
>>>>>>>>> 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?
>>>>>>
>>>>>> What?  This is stable tree backporting, why are you trying to make=
 a
>>>>>> requirement for something that we have never had before?
>>>>>
>>>>> I don't think random patches should be sent to stable just because
>>>>> they appeared in mainline. Plus, I don't think I'm making new rules=
:
>>>>>
>>>>> submit-checklist.rst:
>>>>>
>>>>> 13) Has been build- and runtime tested with and without ``CONFIG_SM=
P``
>>>>> and
>>>>>    ``CONFIG_PREEMPT.``
>>>>>
>>>>> stable-kernel-rules.rst:
>>>>>
>>>>> Rules on what kind of patches are accepted, and which ones are not,=

>>>>> into the "-stable" tree:
>>>>>
>>>>> - It must be obviously correct and tested.
>>>>> - It must fix a real bug that bothers people (not a, "This could be=
 a
>>>>>   problem..." type thing).
>>>>
>>>> So you're saying that this doesn't qualify as a bug?
>>>>
>>>>>> This is a backport of a patch that is already upstream.  If it doe=
sn't
>>>>>> belong in a stable tree, great, let us know that, saying why it is=
 so.
>>>>>
>>>>> See jacek.anaszewski@gmail.com 's explanation.
>>>>
>>>> I might be missing something, but Jacek suggested I pull another pat=
ch
>>>> before this one?
>>>
>>> Just to clarify:
>>>
>>> For 4.14 below patches are chosen correctly:
>>>
>>> [PATCH AUTOSEL for 4.14 065/110] led: core: Fix brightness setting wh=
en
>>> setting delay_off=3D0
>>> [PATCH AUTOSEL for 4.14 094/110] leds: core: Fix regression caused by=

>>> commit 2b83ff96f51d
>>>
>>> For 4.9 both above patches are needed preceded by:
>>>
>>> eb1610b4c273 ("led: core: Fix blink_brightness setting race")
>>>
>>> The issue the patch [PATCH AUTOSEL for 4.14 065/110] fixes was
>>> introduced in 4.7, and thus it should be removed from the series
>>> for 3.18 and 4.4.
>>>
>>
>> It seems only "led: core: Fix brightness setting when setting delay_of=
f=3D0"
>> was applied to 4.9. Could we get the regression fixes backported to 4.=
9 as
>> well?
>=20
> What exact fixes were they?  I'll be glad to apply them if I have a git=

> commit id.
>=20
> thanks,
>=20
> greg k-h
>=20

At least 7b6af2c531 ("leds: core: Fix regression caused by commit
2b83ff96f51d") is missing, causing visible regressions (LEDs not working =
at
all) on some OpenWrt devices. This was fixed in 4.4.121 by reverting the
offending commit, but if I followed the discussion correctly, 4.9 should
get the follow-up commit 7b6af2c531 instead (like 4.14 already did).

Jacek's mail I replied to mentions that eb1610b4c273 ("led: core: Fix
blink_brightness setting race") should be included in 4.9 as well, but I
don't know the impact of the issue it fixes.

Matthias


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