Re: [PATCH v5 3/9] vivid: add dynamic array test control

[Hans Verkuil <hverkuil-cisco@xs4all.nl>]

On 6/15/22 13:53, Laurent Pinchart wrote:
> Hi Hans,
> 
> On Wed, Jun 15, 2022 at 11:14:43AM +0200, Hans Verkuil wrote:
>> Hi Laurent, Xavier,
>>
>> Ignore what I wrote before, I read it with the HEVC patch series in mind, not the dw100
>> series.
>>
>> So let me try again :-)
>>
>> On 6/14/22 23:00, Laurent Pinchart wrote:
>>> Hi Xavier and Hans,
>>>
>>> Thank you for the patch.
>>>
>>> On Tue, May 03, 2022 at 11:39:19AM +0200, Xavier Roumegue wrote:
>>>> From: Hans Verkuil <hverkuil-cisco@xs4all.nl>
>>>>
>>>> Add a dynamic array test control to help test support for this
>>>> feature.
>>>>
>>>> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
>>>> ---
>>>>  drivers/media/test-drivers/vivid/vivid-ctrls.c | 15 +++++++++++++++
>>>>  1 file changed, 15 insertions(+)
>>>>
>>>> diff --git a/drivers/media/test-drivers/vivid/vivid-ctrls.c b/drivers/media/test-drivers/vivid/vivid-ctrls.c
>>>> index e7516dc1227b..7267892dc18a 100644
>>>> --- a/drivers/media/test-drivers/vivid/vivid-ctrls.c
>>>> +++ b/drivers/media/test-drivers/vivid/vivid-ctrls.c
>>>> @@ -34,6 +34,7 @@
>>>>  #define VIVID_CID_U8_4D_ARRAY		(VIVID_CID_CUSTOM_BASE + 10)
>>>>  #define VIVID_CID_AREA			(VIVID_CID_CUSTOM_BASE + 11)
>>>>  #define VIVID_CID_RO_INTEGER		(VIVID_CID_CUSTOM_BASE + 12)
>>>> +#define VIVID_CID_U32_DYN_ARRAY		(VIVID_CID_CUSTOM_BASE + 13)
>>>>  
>>>>  #define VIVID_CID_VIVID_BASE		(0x00f00000 | 0xf000)
>>>>  #define VIVID_CID_VIVID_CLASS		(0x00f00000 | 1)
>>>> @@ -189,6 +190,19 @@ static const struct v4l2_ctrl_config vivid_ctrl_u32_array = {
>>>>  	.dims = { 1 },
>>>>  };
>>>>  
>>>> +static const struct v4l2_ctrl_config vivid_ctrl_u32_dyn_array = {
>>>> +	.ops = &vivid_user_gen_ctrl_ops,
>>>> +	.id = VIVID_CID_U32_DYN_ARRAY,
>>>> +	.name = "U32 Dynamic Array",
>>>> +	.type = V4L2_CTRL_TYPE_U32,
>>>> +	.flags = V4L2_CTRL_FLAG_DYNAMIC_ARRAY,
>>>> +	.def = 50,
>>>> +	.min = 10,
>>>> +	.max = 90,
>>>> +	.step = 1,
>>>> +	.dims = { 100 },
>>>> +};
>>>
>>> To meaningfully test this, don't we need the vivid driver to change the
>>> dimension ? Or is it meant to only test changes made by the application
>>> ?
>>
>> As I understand it the dw100 driver needs a 2 dimensional array control.
>> The size is fixed for each resolution, but if the resolution changes, then
>> this control changes size as well, and it makes sense that when that happens
>> it is also reset to default values.
>>
>> So this isn't a dynamic array at all. It is a standard 2 dimensional array.
>>
>> What is missing in the control framework is a function similar to
>> v4l2_ctrl_modify_range() that can resize an array.
>>
>> v4l2_ctrl_modify_dimensions() would be a good name.
>>
>> I can make something for that if you both agree with this proposal.
> 
> From a userspace point of view, we only need to be able to set the
> control after setting the format. There's no need for control change
> events (but I don't mind if they're there of course, even if I think
> they won't be very usable in practice).
> 
> From an API point of view, I'd like a clear and documented behaviour for
> what happens to the control value when the format is changed. It can be
> a global behaviour, or a control-specific behaviour, I don't mind much.

I'd say it is control specific. In this case you would reset the contents
to default values (presumably values that don't do any warping in this
case).

Regards,

	Hans

> 
>>>> +
>>>>  static const struct v4l2_ctrl_config vivid_ctrl_u16_matrix = {
>>>>  	.ops = &vivid_user_gen_ctrl_ops,
>>>>  	.id = VIVID_CID_U16_MATRIX,
>>>> @@ -1612,6 +1626,7 @@ int vivid_create_controls(struct vivid_dev *dev, bool show_ccs_cap,
>>>>  	dev->ro_int32 = v4l2_ctrl_new_custom(hdl_user_gen, &vivid_ctrl_ro_int32, NULL);
>>>>  	v4l2_ctrl_new_custom(hdl_user_gen, &vivid_ctrl_area, NULL);
>>>>  	v4l2_ctrl_new_custom(hdl_user_gen, &vivid_ctrl_u32_array, NULL);
>>>> +	v4l2_ctrl_new_custom(hdl_user_gen, &vivid_ctrl_u32_dyn_array, NULL);
>>>>  	v4l2_ctrl_new_custom(hdl_user_gen, &vivid_ctrl_u16_matrix, NULL);
>>>>  	v4l2_ctrl_new_custom(hdl_user_gen, &vivid_ctrl_u8_4d_array, NULL);
>>>>  
>