linux-kernel - Re: [PATCH] drm/i2c: tda998x: don't register the connector

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Message-ID: <20160921085738.GA27277@e106950-lin.cambridge.arm.com>
Date:   Wed, 21 Sep 2016 09:57:38 +0100
From:   Brian Starkey <brian.starkey@....com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Daniel Vetter <daniel@...ll.ch>, Liviu.Dudau@....com,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/i2c: tda998x: don't register the connector

Hi Russell,

Are you in a position to be able to test this now?

I believe it should work fine on anything since 4.8-rc1.
(specifically, either of commit e28cd4d0a223 or 79190ea2658a)

Thanks,
Brian

On Tue, Aug 09, 2016 at 11:48:12PM +0100, Russell King - ARM Linux 
wrote:
>On Tue, Aug 09, 2016 at 08:07:24AM +0200, Daniel Vetter wrote:
>> On Mon, Aug 08, 2016 at 05:04:03PM +0100, Brian Starkey wrote:
>> > Hi,
>> >
>> > On Mon, Jul 25, 2016 at 05:08:21PM +0200, Daniel Vetter wrote:
>> > > On Mon, Jul 25, 2016 at 01:54:06PM +0100, Brian Starkey wrote:
>> > > > Hi Russell,
>> > > >
>> > > > On Mon, Jul 25, 2016 at 01:25:04PM +0100, Russell King - ARM Linux wrote:
>> > > > > On Mon, Jul 25, 2016 at 11:55:48AM +0100, Brian Starkey wrote:
>> > > > > > The connector shouldn't be registered until the rest of the whole device
>> > > > > > is set up, so that consistent state is presented to userspace.
>> > > > > >
>> > > > > > As drm_dev_register() now registers all of the connectors anyway,
>> > > > > > there's no need to explicitly do it in individual drivers so remove
>> > > > > > the calls to drm_connector_register()/drm_connector_unregister().
>> > > > > >
>> > > > > > This allows componentised drivers to use tda998x without having racy
>> > > > > > initialisation.
>> > > > >
>> > > > > Is there a corresponding patch for armada-drm so that the cubox doesn't
>> > > > > regress?  Has it already been merged?
>> > > > >
>> > > >
>> > > > A patch for armada-drm to do what?
>> > > >
>> > > > I should perhaps have explicitly mentioned that this change depends
>> > > > on e28cd4d0a223: "drm: Automatically register/unregister all
>> > > > connectors", which is in drm-next.
>> > > >
>> > > > Like my commit message says - after the above commit, all connectors
>> > > > are automatically registered in drm_dev_register() - so I don't
>> > > > anticipate any regression, but I don't have a cubox to test.
>> > > >
>> > > > armada-drm seems to be doing effectively the same thing as arm/hdlcd,
>> > > > which works fine after this patch with no other changes.
>> > > >
>> > > > Let me know if I've missed something; or if you are able to test on
>> > > > cubox that would be great.
>> > >
>> > > Ack from my side on generally nuking drm_connector_register() from
>> > > everywhere except truely hotplugged connectors like dp mst. It should keep
>> > > working for everyone. Only exception is if there's a driver which calls
>> > > drm_dev_register too early (before all connectors are probed), which would
>> > > be a bug anyway.
>> >
>> > Right; the motivation for this change is to fix the init order in
>> > HDLCD and Mali-DP (move drm_dev_register to the end), which we can't
>> > do right now because tda998x expects the DRM device sysfs to be set
>> > up in bind.
>> >
>> > @Daniel: Can I take this as your Acked-by?
>>
>> Sure.
>>
>> > Should this go in via Russell's tree?
>>
>> I can also throw it into drm-misc, if Russell (or someone else) can
>> provide a tested-by for armada. Better safe than sorry ;-)
>
>I can't provide a tested-by for armada yet, because testing it on
>my cubox tree (v4.7) causes a failure.  It probably relies on some
>change merged during the merge window.
>
>-- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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>