From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: John Stultz <john.stultz@linaro.org>
Cc: Orson Zhai <orson.unisoc@gmail.com>,
MyungJoo Ham <myungjoo.ham@samsung.com>,
Kyungmin Park <kyungmin.park@samsung.com>,
Chanwoo Choi <cw00.choi@samsung.com>,
mingmin.ling@unisoc.com, orsonzhai@gmail.com,
jingchao.ye@unisoc.com, Linux PM list <linux-pm@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH] Revert "PM / devfreq: Modify the device name as devfreq(X) for sysfs"
Date: Fri, 21 Feb 2020 08:06:46 +0100 [thread overview]
Message-ID: <20200221070646.GA4103708@kroah.com> (raw)
In-Reply-To: <CALAqxLViRgGE8FsukCJL+doqk_GqabLDCtXBWem+VOGf9xXZdg@mail.gmail.com>
On Thu, Feb 20, 2020 at 11:47:41AM -0800, John Stultz wrote:
> On Thu, Feb 20, 2020 at 11:15 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Fri, Feb 21, 2020 at 01:37:04AM +0800, Orson Zhai wrote:
> > > This reverts commit 4585fbcb5331fc910b7e553ad3efd0dd7b320d14.
> > >
> > > The name changing as devfreq(X) breaks some user space applications,
> > > such as Android HAL from Unisoc and Hikey [1].
> > > The device name will be changed unexpectly after every boot depending
> > > on module init sequence. It will make trouble to setup some system
> > > configuration like selinux for Android.
> > >
> > > So we'd like to revert it back to old naming rule before any better
> > > way being found.
> > >
> > > [1] https://lkml.org/lkml/2018/5/8/1042
> > >
> > > Cc: John Stultz <john.stultz@linaro.org>
> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > Cc: stable@vger.kernel.org
> > > Signed-off-by: Orson Zhai <orson.unisoc@gmail.com>
> > >
> > > ---
> > > drivers/devfreq/devfreq.c | 4 +---
> > > 1 file changed, 1 insertion(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> > > index cceee8b..7dcf209 100644
> > > --- a/drivers/devfreq/devfreq.c
> > > +++ b/drivers/devfreq/devfreq.c
> > > @@ -738,7 +738,6 @@ struct devfreq *devfreq_add_device(struct device *dev,
> > > {
> > > struct devfreq *devfreq;
> > > struct devfreq_governor *governor;
> > > - static atomic_t devfreq_no = ATOMIC_INIT(-1);
> > > int err = 0;
> > >
> > > if (!dev || !profile || !governor_name) {
> > > @@ -800,8 +799,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
> > > devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
> > > atomic_set(&devfreq->suspend_count, 0);
> > >
> > > - dev_set_name(&devfreq->dev, "devfreq%d",
> > > - atomic_inc_return(&devfreq_no));
> > > + dev_set_name(&devfreq->dev, "%s", dev_name(dev));
> > > err = device_register(&devfreq->dev);
> > > if (err) {
> > > mutex_unlock(&devfreq->lock);
> > > --
> > > 2.7.4
> > >
> >
> > Thanks for this, I agree, this needs to get back to the way things were
> > as it seems to break too many existing systems as-is.
> >
> > I'll queue this up in my tree now, thanks.
>
> Oof this old thing. I unfortunately didn't get back to look at the
> devfreq name node issue or the compatibility links, since the impact
> of the regression (breaking the powerHAL's interactions with the gpu)
> wasn't as big as other problems we had. While the regression was
> frustrating, my only hesitancy at this point is that its been this way
> since 4.10, so reverting the problematic patch is likely to break any
> new users since then.
Looks like most users just revert that commit in their trees:
https://source.codeaurora.org/quic/la/kernel/msm-4.14/commit/drivers/devfreq?h=msm-4.14&id=ccf273f6d89ad0fa8032e9225305ad6f62c7770c
So we should be ok here.
thanks,
greg k-h
next prev parent reply other threads:[~2020-02-21 7:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 17:37 [PATCH] Revert "PM / devfreq: Modify the device name as devfreq(X) for sysfs" Orson Zhai
2020-02-20 19:15 ` Greg Kroah-Hartman
2020-02-20 19:47 ` John Stultz
2020-02-20 20:01 ` Greg Kroah-Hartman
2020-02-21 7:06 ` Greg Kroah-Hartman [this message]
2020-02-21 8:11 ` Chanwoo Choi
2020-02-21 11:13 ` Greg Kroah-Hartman
2020-02-21 23:55 ` Chanwoo Choi
2020-02-23 17:54 ` Greg Kroah-Hartman
2020-02-24 2:17 ` Chanwoo Choi
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