Device tree support for WM8994 and WM9713.

Device tree support for WM8994 and WM9713.

[Thomas Abraham]

Hi Mark,

smdkv310 board uses wm8994 and wm9713 audio codecs. I wanted to check
with you if there is any plan on adding device tree support for these
two codecs.

Thanks,
Thomas.

Re: Device tree support for WM8994 and WM9713.

[Mark Brown]

On Tue, Nov 22, 2011 at 11:28:32AM +0530, Thomas Abraham wrote:

> smdkv310 board uses wm8994 and wm9713 audio codecs. I wanted to check
> with you if there is any plan on adding device tree support for these
> two codecs.

I actually have this board.  What state is the -next code in with
respect to device tree, can I usefully run the board (and if I can a
recipie would be very helpful)?  Also, can you tell me where the
bootloader is in the SD card - I've got a binary but no source so I'd
like to start from a fresh card so Id

For WM9713 you shouldn't need any mention in the device tree as for the
way your boards are structured the normal AC'97 discovery mechanisms
should work fine.  However, 

For WM8994 if I can get the board booting with mainline we should be
able to get device tree support for the platform data fairly easily -
the main issue we've got with device tree at the minute is getting a
board which can usefully use it.  Though for your particular board I see
that the existing non-DT code doesn't need any platform data so I'd
expect that you don't need a specific binding at all.  I'll post a patch
that adds a stub binding today or tomorrow.

Re: Device tree support for WM8994 and WM9713.

[Thomas Abraham]

Hi Mark,

On 22 November 2011 18:12, Mark Brown
<broonie@opensource.wolfsonmicro.com> wrote:
> On Tue, Nov 22, 2011 at 11:28:32AM +0530, Thomas Abraham wrote:
>
>> smdkv310 board uses wm8994 and wm9713 audio codecs. I wanted to check
>> with you if there is any plan on adding device tree support for these
>> two codecs.
>
> I actually have this board.  What state is the -next code in with
> respect to device tree, can I usefully run the board (and if I can a
> recipie would be very helpful)?  Also, can you tell me where the
> bootloader is in the SD card - I've got a binary but no source so I'd
> like to start from a fresh card so Id

The DT support for Samsung is available in linux-next and includes
support for smdkv310 board. DT support for pl330 dmac is also
available. I will send the details of using the existing dt support in
a separate email.

>
> For WM9713 you shouldn't need any mention in the device tree as for the
> way your boards are structured the normal AC'97 discovery mechanisms
> should work fine.  However,
>
> For WM8994 if I can get the board booting with mainline we should be
> able to get device tree support for the platform data fairly easily -
> the main issue we've got with device tree at the minute is getting a
> board which can usefully use it.  Though for your particular board I see
> that the existing non-DT code doesn't need any platform data so I'd
> expect that you don't need a specific binding at all.  I'll post a patch
> that adds a stub binding today or tomorrow.
>

Though platform data of wm8994 is not required for smdkv310, there are
other boards 'goni' and 'aquila' which use the platform data. So to
start with, we can ignore the platform data of wm8994 but having full
dt support would be required for other boards.

Thanks,
Thomas.

Re: Device tree support for WM8994 and WM9713.

[Mark Brown]

On Tue, Nov 22, 2011 at 08:09:49PM +0530, Thomas Abraham wrote:

> Though platform data of wm8994 is not required for smdkv310, there are
> other boards 'goni' and 'aquila' which use the platform data. So to
> start with, we can ignore the platform data of wm8994 but having full
> dt support would be required for other boards.

Looking at those they're going to need the regulator bindings for device
tree to do anything useful.  I'd expect that to go into 3.3 but it'll be
hassle propagating the binding bits.

Re: Device tree support for WM8994 and WM9713.

[Vinod Koul]

On Tue, 2011-11-22 at 19:43 +0000, Mark Brown wrote:
> On Tue, Nov 22, 2011 at 08:09:49PM +0530, Thomas Abraham wrote:
> 
> > Though platform data of wm8994 is not required for smdkv310, there are
> > other boards 'goni' and 'aquila' which use the platform data. So to
> > start with, we can ignore the platform data of wm8994 but having full
> > dt support would be required for other boards.
> 
> Looking at those they're going to need the regulator bindings for device
> tree to do anything useful.  I'd expect that to go into 3.3 but it'll be
> hassle propagating the binding bits.
I have a question here, how does using DT to a codec (which can be used
even on a system where there is no DT present) be generic and break the
assumption that codec does not know anything about the system it
operates in?
This should be done for machine or cpu driver which know if system has
DT or not?

-- 
~Vinod

Re: Device tree support for WM8994 and WM9713.

[Mark Brown]

On Wed, Nov 23, 2011 at 11:33:53AM +0530, Vinod Koul wrote:
> On Tue, 2011-11-22 at 19:43 +0000, Mark Brown wrote:

> > Looking at those they're going to need the regulator bindings for device
> > tree to do anything useful.  I'd expect that to go into 3.3 but it'll be
> > hassle propagating the binding bits.

> I have a question here, how does using DT to a codec (which can be used
> even on a system where there is no DT present) be generic and break the
> assumption that codec does not know anything about the system it
> operates in?
> This should be done for machine or cpu driver which know if system has
> DT or not?

When drivers implement device tree support this should be done in
addition to rather than instead of platform data support so other
platforms should not be affected.  A very common way of implementing
this is that the device tree parsing code translates the device tree
into a platform data structure and then the driver runs off a copy of
the platform data structure.