Template for a new driver

Template for a new driver

[Devin Heitmueller]

Hello,

I am writing a new driver for a video decoder, and wanted to ask if
there was any particular driver people would suggest as a model to
look at for new drivers.  For example, I am not completely familiar
with which interfaces are deprecated, and want to make sure I use a
driver as a template that reflects the latest standards/conventions.

Suggestions welcome.

Thanks in advance,

Devin

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RE: Template for a new driver

[Hiremath, Vaibhav]

Thanks,
Vaibhav Hiremath

> -----Original Message-----
> From: video4linux-list-bounces@redhat.com [mailto:video4linux-list-
> bounces@redhat.com] On Behalf Of Devin Heitmueller
> Sent: Monday, December 15, 2008 6:31 AM
> To: V4L
> Subject: Template for a new driver
> 
> Hello,
> 
> I am writing a new driver for a video decoder, and wanted to ask if
> there was any particular driver people would suggest as a model to
> look at for new drivers.  For example, I am not completely familiar
> with which interfaces are deprecated, and want to make sure I use a
> driver as a template that reflects the latest standards/conventions.
> 
> Suggestions welcome.
> 
[Hiremath, Vaibhav] I would suggest using new sub-device framework which recently Hans has submitted, since all other frameworks are going to be deprecated.
Please refer to the mail-chain for more info - 

http://marc.info/?l=linux-video&m=122756460125873&w=2

http://marc.info/?l=linux-video&m=122808129216519&w=2


> Thanks in advance,
> 
> Devin
> 
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> Devin J. Heitmueller
> http://www.devinheitmueller.com
> AIM: devinheitmueller
> 
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Re: Template for a new driver

[Hans Verkuil]

On Monday 15 December 2008 02:01:14 Devin Heitmueller wrote:
> Hello,
>
> I am writing a new driver for a video decoder, and wanted to ask if
> there was any particular driver people would suggest as a model to
> look at for new drivers.  For example, I am not completely familiar
> with which interfaces are deprecated, and want to make sure I use a
> driver as a template that reflects the latest standards/conventions.
>
> Suggestions welcome.
>
> Thanks in advance,
>
> Devin

Hi Devin,

You definitely want to use the new v4l2_subdev framework for this. Read 
Documentation/video4linux/v4l2-framework.txt for more info.

A good example template is probably saa7115.c. Not as big and 
complicated as the audio-video decoder cx25840, but still a good 
non-trivial example.

I also recommend using struct v4l2_i2c_driver_data if you desire to be 
compatible with older kernels. The main reason for having this struct 
is to hide all the ugly kernel #ifdefs.

Regards,

	Hans

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Re: Template for a new driver

[Devin Heitmueller]

On Mon, Dec 15, 2008 at 5:06 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
> On Monday 15 December 2008 02:01:14 Devin Heitmueller wrote:
>> Hello,
>>
>> I am writing a new driver for a video decoder, and wanted to ask if
>> there was any particular driver people would suggest as a model to
>> look at for new drivers.  For example, I am not completely familiar
>> with which interfaces are deprecated, and want to make sure I use a
>> driver as a template that reflects the latest standards/conventions.
>>
>> Suggestions welcome.
>>
>> Thanks in advance,
>>
>> Devin
>
> Hi Devin,
>
> You definitely want to use the new v4l2_subdev framework for this. Read
> Documentation/video4linux/v4l2-framework.txt for more info.
>
> A good example template is probably saa7115.c. Not as big and
> complicated as the audio-video decoder cx25840, but still a good
> non-trivial example.
>
> I also recommend using struct v4l2_i2c_driver_data if you desire to be
> compatible with older kernels. The main reason for having this struct
> is to hide all the ugly kernel #ifdefs.
>
> Regards,
>
>        Hans

Thanks for the feedback.  Because I didn't wait for more responses
last night, I ended up using the cx25840 driver as the base, which
seems to have been a good choice.

Cheers,

Devin

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