Media system Summit

Media system Summit

[Mauro Carvalho Chehab]

Em 11-07-2012 05:09, James Bottomley escreveu:
> Hi All,
> 
> We have set aside the second day of the kernel summit (Tuesday 28
> August) as mini-summit day.  So far we have only the PCI mini summit on
> this day

Not sure what happened (or maybe my proposal were not clear enough), but 
I've submitted a proposal to have a media system summit on KS/2011.
Last year was very productive for media developers, so we'd like to do
it again ;)


Message-ID: <4FEC74AB.6070501@redhat.com>
Date: Thu, 28 Jun 2012 12:13:47 -0300
From: Mauro Carvalho Chehab <mchehab@redhat.com>

[Ksummit-2012-discuss] [ATTEND] media subsystem

I'd like to have media subsystem discussions this year's at kernel summit. 
The media subsystem is one of the most active driver subsystem, and there are lots of 
things there that require face-to-face discussions, not only between subsystem developers, 
but also with other maintainers. In special, during KS/2011, it was identified the need 
of interacting with video and audio system people, in order to solve some common issues, 
like HDMI CEC and audio/video synchronization. 

The increasing complexity of SoC designs used by media devices requires API
extensions at the media APIs in order to proper expose and control all hardware 
functionality on a standard way. A new API to better allow negotiating userspace
and Kernelspace capabilities seem to be required.

More discussions with regards to shared resources locking is needed, on devices that
implement multiple API's, but not a the same time.

The incompatibility between udev-182 and the existing drivers will also require lots
of discussions, as that affects 64 media drivers, and changing them to comply with
the current requirement of using request_firmware_nowait() won't work on several
drivers. So, a solution (or a set of solutions) needs to be found, in order to fix
such incompatibility.

Thanks,
Mauro

Re: Media system Summit

[Sylwester Nawrocki]

Hi Mauro,

On 07/12/2012 05:18 AM, Mauro Carvalho Chehab wrote:
> Em 11-07-2012 05:09, James Bottomley escreveu:
>> Hi All,
>>
>> We have set aside the second day of the kernel summit (Tuesday 28
>> August) as mini-summit day.  So far we have only the PCI mini summit on
>> this day
> 
> Not sure what happened (or maybe my proposal were not clear enough), but
> I've submitted a proposal to have a media system summit on KS/2011.
> Last year was very productive for media developers, so we'd like to do
> it again ;)
> 
> 
> Message-ID:<4FEC74AB.6070501@redhat.com>
> Date: Thu, 28 Jun 2012 12:13:47 -0300
> From: Mauro Carvalho Chehab<mchehab@redhat.com>
> 
> [Ksummit-2012-discuss] [ATTEND] media subsystem
> 
> I'd like to have media subsystem discussions this year's at kernel summit.
> The media subsystem is one of the most active driver subsystem, and there are lots of
> things there that require face-to-face discussions, not only between subsystem developers,
> but also with other maintainers. In special, during KS/2011, it was identified the need
> of interacting with video and audio system people, in order to solve some common issues,
> like HDMI CEC and audio/video synchronization.
> 
> The increasing complexity of SoC designs used by media devices requires API
> extensions at the media APIs in order to proper expose and control all hardware
> functionality on a standard way. A new API to better allow negotiating userspace
> and Kernelspace capabilities seem to be required.
> 
> More discussions with regards to shared resources locking is needed, on devices that
> implement multiple API's, but not a the same time.
> 
> The incompatibility between udev-182 and the existing drivers will also require lots
> of discussions, as that affects 64 media drivers, and changing them to comply with
> the current requirement of using request_firmware_nowait() won't work on several
> drivers. So, a solution (or a set of solutions) needs to be found, in order to fix
> such incompatibility.

I'd like to add a "Common device tree bindings for media devices" topic to
the agenda for consideration.

There were some activities on creating device tree bindings for Samsung and
SH Mobile SoCs but this didn't really kick off yet and a face to face discussions
could help to bring device tree support in media subsystem to the level many
other subsystems already have.

--

Thanks,
Sylwester

Re: [Ksummit-2012-discuss] Media system Summit

[Mark Brown]

On Thu, Jul 12, 2012 at 10:08:04AM +0200, Sylwester Nawrocki wrote:

> I'd like to add a "Common device tree bindings for media devices" topic to
> the agenda for consideration.

It'd be nice to get this to join up with ASoC...

Re: [Ksummit-2012-discuss] Media system Summit

[Olof Johansson]

On Thu, Jul 12, 2012 at 9:18 AM, Mark Brown
<broonie@opensource.wolfsonmicro.com> wrote:
> On Thu, Jul 12, 2012 at 10:08:04AM +0200, Sylwester Nawrocki wrote:
>
>> I'd like to add a "Common device tree bindings for media devices" topic to
>> the agenda for consideration.
>
> It'd be nice to get this to join up with ASoC...


There's a handful of various subsystems that have similar topics,
maybe slice it the other way and do a device-tree/ACPI breakout that
cuts across the various areas instead?

Communication really needs to be two-way: Crafting good bindings for a
complex piece of hardware isn't trivial and having someone know both
the subsystem and device tree principles is rare. At least getting all
those people into the same room would be good.

There's obvious overlap with ARM here as well, since it's one of the
current big pushers of DT use, but I think it would be better to hold
this as a separate breakout from that.


-Olof

Re: [Ksummit-2012-discuss] Media system Summit

[Mark Brown]

On Thu, Jul 12, 2012 at 09:48:23AM -0700, Olof Johansson wrote:

> There's a handful of various subsystems that have similar topics,
> maybe slice it the other way and do a device-tree/ACPI breakout that
> cuts across the various areas instead?

> Communication really needs to be two-way: Crafting good bindings for a
> complex piece of hardware isn't trivial and having someone know both
> the subsystem and device tree principles is rare. At least getting all
> those people into the same room would be good.

> There's obvious overlap with ARM here as well, since it's one of the
> current big pushers of DT use, but I think it would be better to hold
> this as a separate breakout from that.

I think this is an excellent idea.

Re: [Ksummit-2012-discuss] Media system Summit

[Hans Verkuil]

On Thu July 12 2012 18:48:23 Olof Johansson wrote:
> On Thu, Jul 12, 2012 at 9:18 AM, Mark Brown
> <broonie@opensource.wolfsonmicro.com> wrote:
> > On Thu, Jul 12, 2012 at 10:08:04AM +0200, Sylwester Nawrocki wrote:
> >
> >> I'd like to add a "Common device tree bindings for media devices" topic to
> >> the agenda for consideration.
> >
> > It'd be nice to get this to join up with ASoC...
> 
> 
> There's a handful of various subsystems that have similar topics,
> maybe slice it the other way and do a device-tree/ACPI breakout that
> cuts across the various areas instead?
> 
> Communication really needs to be two-way: Crafting good bindings for a
> complex piece of hardware isn't trivial and having someone know both
> the subsystem and device tree principles is rare. At least getting all
> those people into the same room would be good.

I'm not so sure: I think that most decisions that need to be made are
quite subsystem specific. Trying to figure out how to implement DT for
multiple subsystems in one workshop seems unlikely to succeed, simply
because of lack of time. I also don't think there is much overlap between
subsystems in this respect, so while the DT implementation for one subsystem
is discussed, the representatives of other subsystems are twiddling their
thumbs.

It might be more productive to have one or two DT experts around who
rotate over the various workshops that have to deal with the DT and can
offer advice.

Regards,

	Hans

> 
> There's obvious overlap with ARM here as well, since it's one of the
> current big pushers of DT use, but I think it would be better to hold
> this as a separate breakout from that.
> 
> 
> -Olof
> --
> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: [Ksummit-2012-discuss] Media system Summit

[Guennadi Liakhovetski]

On Thu, 12 Jul 2012, Hans Verkuil wrote:

> On Thu July 12 2012 18:48:23 Olof Johansson wrote:
> > On Thu, Jul 12, 2012 at 9:18 AM, Mark Brown
> > <broonie@opensource.wolfsonmicro.com> wrote:
> > > On Thu, Jul 12, 2012 at 10:08:04AM +0200, Sylwester Nawrocki wrote:
> > >
> > >> I'd like to add a "Common device tree bindings for media devices" topic to
> > >> the agenda for consideration.
> > >
> > > It'd be nice to get this to join up with ASoC...
> > 
> > 
> > There's a handful of various subsystems that have similar topics,
> > maybe slice it the other way and do a device-tree/ACPI breakout that
> > cuts across the various areas instead?
> > 
> > Communication really needs to be two-way: Crafting good bindings for a
> > complex piece of hardware isn't trivial and having someone know both
> > the subsystem and device tree principles is rare. At least getting all
> > those people into the same room would be good.
> 
> I'm not so sure: I think that most decisions that need to be made are
> quite subsystem specific. Trying to figure out how to implement DT for
> multiple subsystems in one workshop seems unlikely to succeed, simply
> because of lack of time. I also don't think there is much overlap between
> subsystems in this respect, so while the DT implementation for one subsystem
> is discussed, the representatives of other subsystems are twiddling their
> thumbs.
> 
> It might be more productive to have one or two DT experts around who
> rotate over the various workshops that have to deal with the DT and can
> offer advice.

I'm sure everyone has seen this, but just to have it mentioned here:

<a 
href="http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/50755">
shameless self-advertisement</a>

I'm not sure whether the overlap with other subsystems is large or not, 
but there definitely is some, also with video (fbdev / drm), e.g., 
http://thread.gmane.org/gmane.linux.drivers.devicetree/17495

As for whether or not discuss DT for various subsystems together - why not 
do both? First short sessions in each subsystems, of course, this would 
only work if proposals have been prepared beforehand and at least 
preliminary discussions on the MLs have taken place, and then another 
(also short) combined session? Of course, it also depends on how much time 
we can and want to dedicate to this.

Thanks
Guennadi

> Regards,
> 
> 	Hans
> 
> > 
> > There's obvious overlap with ARM here as well, since it's one of the
> > current big pushers of DT use, but I think it would be better to hold
> > this as a separate breakout from that.
> > 
> > 
> > -Olof
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-media" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

Re: [Ksummit-2012-discuss] Media system Summit

[Olof Johansson]

On Thu, Jul 12, 2012 at 2:05 PM, Guennadi Liakhovetski
<g.liakhovetski@gmx.de> wrote:
> On Thu, 12 Jul 2012, Hans Verkuil wrote:
>
>> On Thu July 12 2012 18:48:23 Olof Johansson wrote:
>> > On Thu, Jul 12, 2012 at 9:18 AM, Mark Brown
>> > <broonie@opensource.wolfsonmicro.com> wrote:
>> > > On Thu, Jul 12, 2012 at 10:08:04AM +0200, Sylwester Nawrocki wrote:
>> > >
>> > >> I'd like to add a "Common device tree bindings for media devices" topic to
>> > >> the agenda for consideration.
>> > >
>> > > It'd be nice to get this to join up with ASoC...
>> >
>> >
>> > There's a handful of various subsystems that have similar topics,
>> > maybe slice it the other way and do a device-tree/ACPI breakout that
>> > cuts across the various areas instead?
>> >
>> > Communication really needs to be two-way: Crafting good bindings for a
>> > complex piece of hardware isn't trivial and having someone know both
>> > the subsystem and device tree principles is rare. At least getting all
>> > those people into the same room would be good.
>>
>> I'm not so sure: I think that most decisions that need to be made are
>> quite subsystem specific. Trying to figure out how to implement DT for
>> multiple subsystems in one workshop seems unlikely to succeed, simply
>> because of lack of time. I also don't think there is much overlap between
>> subsystems in this respect, so while the DT implementation for one subsystem
>> is discussed, the representatives of other subsystems are twiddling their
>> thumbs.
>>
>> It might be more productive to have one or two DT experts around who
>> rotate over the various workshops that have to deal with the DT and can
>> offer advice.
>
> I'm sure everyone has seen this, but just to have it mentioned here:
>
> <a
> href="http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/50755">
> shameless self-advertisement</a>

I hadn't seen it, since you didn't cc devicetree-discuss. Well, I'm
also generally behind on list email right now since I am travelling
but I couldn't find it in any list folder I subscribe to.

> As for whether or not discuss DT for various subsystems together - why not
> do both? First short sessions in each subsystems, of course, this would
> only work if proposals have been prepared beforehand and at least
> preliminary discussions on the MLs have taken place, and then another
> (also short) combined session? Of course, it also depends on how much time
> we can and want to dedicate to this.

The agenda for such a day should probably be partially broken down per
subsystem, yes, and it would make sense for people from the various
areas to describe the kind of setup that they need to be able to
define, similar to how you did in your writeup above.

In some cases it would be a matter of in-person
review/discussion/arguments of already proposed bindings, in other
cases it would probably be a seeding discussion for upcoming bindings
instead. Having the latter piggy-back on hearing what's discussed with
the former category would likely be a good idea.


-Olof

Re: Media system Summit

[Rémi Denis-Courmont]

	Hello all,

Le jeudi 12 juillet 2012 06:18:08 Mauro Carvalho Chehab, vous avez écrit :
> > We have set aside the second day of the kernel summit (Tuesday 28
> > August) as mini-summit day.  So far we have only the PCI mini summit on
> > this day
> 
> Not sure what happened (or maybe my proposal were not clear enough), but
> I've submitted a proposal to have a media system summit on KS/2011.
> Last year was very productive for media developers, so we'd like to do
> it again ;)

Do you guys expect to discuss anything relevant to userland? (V4L? DVB? ...?)

-- 
Rémi Denis-Courmont
http://www.remlab.net/
http://fi.linkedin.com/in/remidenis