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

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

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.

> >> +
> >>  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);
> >>  

-- 
Regards,

Laurent Pinchart