2019-11-01 11:33:41

by Ricardo Ribalda Delgado

Subject: [PATCH v3 2/5] media: v4l2_ctrl: Add const pointer to ctrl_ptr

This pointer is used to point to data that is constant. Thanks to this
we can avoid a lot of casting and we make more clear when the data is
constant or variable.

Suggested-by: Hans Verkuil <[email protected]>
Signed-off-by: Ricardo Ribalda Delgado <[email protected]>
---
include/media/v4l2-ctrls.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
index 78a97b10c89e..7db9e719a583 100644
--- a/include/media/v4l2-ctrls.h
+++ b/include/media/v4l2-ctrls.h
@@ -56,6 +56,7 @@ struct poll_table_struct;
* @p_hevc_slice_params: Pointer to an HEVC slice parameters structure.
* @p_area: Pointer to an area.
* @p: Pointer to a compound value.
+ * @p_const: Pointer to a constant compound value.
*/
union v4l2_ctrl_ptr {
s32 *p_s32;
@@ -78,6 +79,7 @@ union v4l2_ctrl_ptr {
struct v4l2_ctrl_hevc_slice_params *p_hevc_slice_params;
struct v4l2_area *p_area;
void *p;
+ const void *p_const;
};

/**
--
2.24.0.rc1

2019-11-04 09:50:11

by Hans Verkuil

Subject: Re: [PATCH v3 2/5] media: v4l2_ctrl: Add const pointer to ctrl_ptr

Hi Ricardo,

On 11/1/19 12:23 PM, Ricardo Ribalda Delgado wrote:
> This pointer is used to point to data that is constant. Thanks to this
> we can avoid a lot of casting and we make more clear when the data is
> constant or variable.
>
> Suggested-by: Hans Verkuil <[email protected]>
> Signed-off-by: Ricardo Ribalda Delgado <[email protected]>
> ---
> include/media/v4l2-ctrls.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
> index 78a97b10c89e..7db9e719a583 100644
> --- a/include/media/v4l2-ctrls.h
> +++ b/include/media/v4l2-ctrls.h
> @@ -56,6 +56,7 @@ struct poll_table_struct;
> * @p_hevc_slice_params: Pointer to an HEVC slice parameters structure.
> * @p_area: Pointer to an area.
> * @p: Pointer to a compound value.
> + * @p_const: Pointer to a constant compound value.
> */
> union v4l2_ctrl_ptr {
> s32 *p_s32;
> @@ -78,6 +79,7 @@ union v4l2_ctrl_ptr {
> struct v4l2_ctrl_hevc_slice_params *p_hevc_slice_params;
> struct v4l2_area *p_area;
> void *p;
> + const void *p_const;
> };
>
> /**
>

This addition makes it possible to use const void pointers elsewhere in
the control framework.

E.g. in std_equal you can use p_const in the memcmp at the end.

Can you go through the v4l2-ctrls.c source and replace .p by .p_const
where it makes sense?

Obviously this would be a separate patch.

Regards,

Hans