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Subject: Re: [PATCH 4.16 REGRESSION fix 1/2] Revert "Bluetooth: hci_bcm:
 Streamline runtime PM code"
From: Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20180315081408.GC4615@wunner.de>
Date: Thu, 15 Mar 2018 14:15:10 +0100
Cc: Hans de Goede <hdegoede@redhat.com>,
        "Gustavo F. Padovan" <gustavo@padovan.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        =?utf-8?Q?Fr=C3=A9d=C3=A9ric_Danis?= <frederic.danis.oss@gmail.com>,
        Linux Bluetooth mailing list
        <linux-bluetooth@vger.kernel.org>, linux-serial@vger.kernel.org,
        linux-acpi@vger.kernel.org, "Robert R. Howell" <rhowell@uwyo.edu>
Message-Id: <2F4B2A06-7ABD-49D6-BCC8-2885F87FE00B@holtmann.org>
References: <20180314220603.7559-1-hdegoede@redhat.com>
 <20180314220603.7559-2-hdegoede@redhat.com>
 <20180314221603.GB28738@wunner.de>
 <807b74cb-2222-2d47-12c2-0415a9027102@redhat.com>
 <20180314223813.GD28738@wunner.de>
 <066d03cc-6dd0-7eca-f8cc-78e81277459c@redhat.com>
 <20180315081408.GC4615@wunner.de>
To: Lukas Wunner <lukas@wunner.de>
Sender: linux-serial-owner@vger.kernel.org
List-ID: <linux-bluetooth.vger.kernel.org>

Hi Lukas,

>>>> We're quite far into the cycle already and this is a serious regression,
>>>> also nothing of great value is lost by the revert, the original commit
>>>> was a minor cleanup which turns out to have bad side-effects, a simple
>>>> revert really is the best solution here, esp. in this point of the cycle.
>>> 
>>> Just an hour ago he sent me the patch to look over it.  And we're at
>>> least two and a half weeks away from v4.16.
>> 
>> No we are *only* two and a half weeks away from v4.16 (worst case scenario)
>> and Linus does not like getting last minute fixes.
> 
> That doesn't preclude allowing a few hours to discuss things.
> There is never such a rush.  In the present case, a new contributor
> was willing to debug the issue and submit a patch.  Onboarding new
> contributors is important and IMO it's worth waiting a few days for
> them to sort things out, even if it means a regression stays present
> a little longer.  I'm sorry that it meant you wasted time debugging
> it in parallel.
> 
> That said, when submitting the patch I clearly failed to notice that
> for devices using autosuspend, pm_request_resume() doesn't update
> the last usage timestamp.  While that could be fixed by calling
> pm_runtime_mark_last_busy() before pm_request_resume(), it doesn't
> seem to be customary as a look at all the call sites of
> pm_request_resume() shows.  The original three-line sequence,
> although quite verbose, appears to be what is commonly used in such
> a case.  For this reason reverting back to the original version
> seems justified.

there is no reason to rush this through. With a properly worded commit message that explain the reason, I have no problem to do a last minute -rc inclusion.

However what I like to have is a single patch with all Acks and also CC: stable tags if required that we can just send off in the direction towards Linus. I saw there is an alternative patch on the mailing list. So I would like to have a good conclusion on what goes to -rc and that we all agree.

Regards

Marcel