Re: [PATCH v2] v4l: subdev: Add pad config allocator and init

[Hans Verkuil <hverkuil@xs4all.nl>]

On 05/25/2015 01:21 PM, Laurent Pinchart wrote:
> Hi Hans,
> 
> On Monday 25 May 2015 00:25:36 Hans Verkuil wrote:
>> On 05/24/2015 11:10 PM, Laurent Pinchart wrote:
>>> From: Laurent Pinchart <laurent.pinchart@linaro.org>
>>>
>>> Add a new subdev operation to initialize a subdev pad config array, and
>>> a helper function to allocate and initialize the array. This can be used
>>> by bridge drivers to implement try format based on subdev pad
>>> operations.
>>>
>>> Signed-off-by: Laurent Pinchart <laurent.pinchart@linaro.org>
>>> Acked-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
>>
>> Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
>>
>> Note that before this goes in there should be at least one subdev driver
>> that implements init_cfg(). Perhaps adv7604?
> 
> I fully agree, this needs to be used by at least one subdev driver.
> 
> I'd go even further, I'd like to see v4l2_subdev_alloc_pad_config() used by a 
> bridge driver, to implement VIDIOC_TRY_FMT. I've originally written the patch 
> to implement VIDIOC_TRY_FMT (and VIDIOC_ENUM_FRAMESIZES) in a driver I'm 
> developing, but it's not ready for submission to mainline yet.
> 
> Do you think a subdev driver is enough, or do we need a bridge too in order to 
> merge this patch ?

Ideally a bridge as well, but the one that needs it first is soc-camera, which
generally is a pain. On the other hand, it is a good non-trivial use-case.

Regards,

	Hans

> 
>>> ---
>>>
>>>  drivers/media/v4l2-core/v4l2-subdev.c | 19 ++++++++++++++++++-
>>>  include/media/v4l2-subdev.h           | 10 ++++++++++
>>>  2 files changed, 28 insertions(+), 1 deletion(-)
>>>
>>> Changes since v1:
>>>
>>> - Added v4l2_subdev_free_pad_config
>