From: Greg KH <gregkh@linuxfoundation.org>
To: Pavel Machek <pavel@denx.de>, Guru Das Srinagesh <gurus@codeaurora.org>
Cc: linux-leds@vger.kernel.org,
Jacek Anaszewski <jacek.anaszewski@gmail.com>,
Dan Murphy <dmurphy@ti.com>,
linux-kernel@vger.kernel.org,
Subbaraman Narayanamurthy <subbaram@codeaurora.org>
Subject: Re: [PATCH 1/2] leds: Add flag to keep trigger always
Date: Mon, 30 Sep 2019 19:27:43 +0200 [thread overview]
Message-ID: <20190930172743.GA2409822@kroah.com> (raw)
In-Reply-To: <20190930172239.GA26107@amd>
On Mon, Sep 30, 2019 at 07:22:39PM +0200, Pavel Machek wrote:
> On Mon 2019-09-30 15:39:02, Greg KH wrote:
> > On Sat, Aug 10, 2019 at 09:13:22AM +0200, Pavel Machek wrote:
> > > On Fri 2019-08-09 17:52:46, Guru Das Srinagesh wrote:
> > > > From: Subbaraman Narayanamurthy <subbaram@codeaurora.org>
> > > >
> > > > Commit 0013b23d66a2768f5babbb0ea9f03ab067a990d8 ("leds: disable triggers
> > > > on brightness set") removes the trigger on an LED class device when
> > > > brightness is set to 0. However, there are some LED class devices which
> > > > need the trigger not to be removed. In a use case like camera flash,
> > > > camera flash driver passes in a trigger device to LED class driver. If
> > > > the trigger is removed when the brightness is set to 0, this will affect
> > > > the clients using those triggers. Hence add a flag to always keep the
> > > > trigger even when brightness is set to 0.
> > >
> > > No.
> > >
> > > Yes, it would affect those clients. Don't do it, then. It is
> > > root-only operation.
> >
> > I don't understand. The original commit broke userspace operations.
> > Shouldn't it be reverted, or fixed this way in order to have userspace
> > work properly again?
>
> So, what it is exactly that is not working? :-). Yes, root can
> disconnect LED from v4l2 interface; he can also connect it
> back. Documentation says that happens.
>
> Yes, root can do stupid things.
>
> Commit 0013b23d66a2768f5babbb0ea9f03ab067a990d8 is from 2008. I'd
> prefer we did not apply it in 2008, but...
Ah, my fault, I thought this was a new commit.
Guru, what are you doing here that this is required all of a sudden? No
other kernel seems to need these changes, what is different in your
Android userspace that requires this patch series?
thanks,
greg k-h
next prev parent reply other threads:[~2019-09-30 21:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-10 0:52 [PATCH 1/2] leds: Add flag to keep trigger always Guru Das Srinagesh
2019-08-10 0:52 ` [PATCH 2/2] leds: triggers: Don't remove trigger if LED_KEEP_TRIGGER flag is set Guru Das Srinagesh
2019-08-10 7:13 ` [PATCH 1/2] leds: Add flag to keep trigger always Pavel Machek
2019-09-30 13:39 ` Greg KH
2019-09-30 17:22 ` Pavel Machek
2019-09-30 17:27 ` Greg KH [this message]
2019-10-04 20:09 ` Guru Das Srinagesh
2019-10-08 7:47 ` Pavel Machek
2019-10-10 0:52 ` Guru Das Srinagesh
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